That’s what I was hoping to hear Nick . I certainly would not go stirring up a wasps nest if not needed . Thanks . 

Those garage gnomes!

Yes haha! I think it will be around the same size or smaller than my driveshafts which is novel 

I’d be seriously wary of involving the DVLA.  That way lies huge pain and expense.   This is an existing, registered vehicle and chassis mods (as I understand it) are restricted to a few tabs welded to the main rails with the basic structure unaltered. So long as you have your 8 points (may be tight?!) and your insurance company are informed, you should be good. DO get it MoT’d though!

Ooof…. Is your diff one of the long-nosed ones? Propshaft is going to be REALLY short!

I see your point, but I am aiming to install the 6pot 6-8inchs back as to avoid having a bonnet bulge. With the mx5 gearbox attached I’m aware this is not possible without major chassis modification, which is exactly what i intend to do. I will be cutting the chassis rails just in front of the bulkhead and just behind my gearbox mount and removing the 6-8inch from behind there and then re splice those same sections in at the front if that makes sense? I’ll of course have to modify the body to suit. not much on my triumph is original and it’s a cheap car that I brought back from the dead, so I don’t mind chopping it up and having some fun with it, I’ve learnt a lot more this way than from my 4 years in college ‘learning’ about mechanics 

Your bell housing may be a bit shorter than mine, but I also think you are basing everything on the 4 cylinder engine position which may come back to bite when you fit the 6 as the engine/box joint is 1” further back on the 6 pot.

Yes it’s far more than I anticipated. Doesn’t make sense for the average driver to go for the conversion in my opinion, but for some reason I just really wanted to do it, so I did

Ah yes starter placement, something I forgot to mention, it will definitely require some light reshaping of my exhaust tubular manifold which I am a little unhappy about but it’s got to be done!    I didn’t check the clutch pressure plate to  clearance but it seems to turn fine so I guess I got lucky lol. ive read your very thorough post on your gearbox conversion, its impressive work. I saw your complication with the reverse switch, fortunately for me because I’ve shortened the bell housing it doesn’t interfere with the H frame which is nice. what am I doing about Speedo drive?  that’s a good question, I believe I’ll cross that bridge when I come to it. I’m sure I’ll manage to cobble together some form of mutilated drive to get it working. I’ve seen you had difficulty with access but mine looks okay so we live in hope, I think that’s also due to the box itself being shorter. hopefully my gearbox is okay but if it isn’t I shall simply replace it. All of the modifications I have done are bolt on to the gearbox so I can chop and swap at will.    I am yet to test my clutch release mechanism due to my clearance issue with the chassis and I am quite anxious to do so as I am anticipating some form of resistance as per usual. i should balance my prop, and i will at somepoint or I’ll get a custom one made, but the prop is so short now because of my modification I’m hoping to will ratify some of the vibration it could cause, wish me luck! 

Oh yes - it’s a lot of work!  Quite tricky work too. We’ve done a couple now - one for my GT6 which is fully documented on here and Chris’s “Frankenspit” which has an MX5 box modified to fit a Ford Sigma SE. Both were a bloody mission. Sam, I do like the idea of machining down the flywheel to take the Mazda ring-gear. I did consider it, but chose not to in the end for several smallish reasons, some of which you’ve encountered! Still could well be the easier option, though you may struggle with starter placement? GT6 clutch must be really tight with the ring-gear and inside the bellhousing? We machined the flywheel on the GT6 to take a ball bearing race for the spigot bearing and it uses a concentric clutch base on a Vauxhall Omega slave cylinder. The Spitfire has an oilite bush in the crank as the bell housing is really short. This has created difficulties with the clutch release as there’s barely room even for a concentric slave and the right make of clutch has to used to clear everything!  Both cars have the shift position moved to the Triumph position, which has meant re-inventing the shifter mech. Also a lot of work. Your approach is probably better in many respects even if it does mean tunnel mods. Watch out for the reversing light switch - it wants to share space with the H-frame! Both have bespoke propshafts build by specialists. There’s very little between driver and propshaft and having seen the results of a failed prop on a more robust vehicle…., I’m chicken!! Rear mount and chassis clearance are also a PITA. Both ours are further back than yours so less interference. No cutting needed just some re-shaping of the lips. What are you doing about speedo drive? Good luck with your actual gearbox. Both of ours are noisy in all indirect gears and fussy into to second gear - a bit too much like the Triumph boxes! We have others, which may or may not be better. Rebuilds are quite involved and parts not very easy to get as they are still considered disposable!