Brian, I typed this out yesterday, but it hung up and didn't post. So here it is anyway, even though I see from your comments it is redundant.........but do check the next to last line.....Bruce's ideas on preferred shift pattern come from his experience with Australian and New Zealand racers! Not always the same as us Brits!
Good to talk it through with Bruce as suggested. However, the UK supplier of TTi boxes is Minnovation. Talk to them as well.
They mainly build Seeley G50 style bikes with TTi boxes in, and belt drives! They do have a considerable general knowledge and prepare some nice bikes, though I doubt they have a great specific knowledge of the Dommi, or the Manx clutch and it's similarity or otherwise to the AMC clutch. I doubt they have the mainshaft you need in stock, but when you know what that is from Bruce, do check.
If you buy direct from Bruce you will be rolling the dice on import charges. From Minnovation you should get a firm quote.
You are also going to need to be clear which way you want your gear change to operate, and be able to express that in terms of clockwise or anticlockwise at the gear change shaft!
You don't mention how many speeds you want or if you need a kickstart. Again you will need to be clear!
