Long term project: year two. TriBSA cafe racer.

I started collecting parts about a year ago for some sort of ground up build. I wasn't sure at the time of what I wanted, only that I wanted to use a triumph 650 pre unit engine in some frame other than a standard triumph frame aka a special. Well after helping my neighbor rescue his 55 A10 from 40 years of deep storage, I started thinking about the beauty of the A10 frame. TriBSA cafe's are much less common than the Triton (which everybody seems to be building these days - most of which are not done very well).  I have a frame and swing arm, a stock oil tank if needed, a possible set of forks, though I'm thinking Norton Roadholders, a massive twin dual lead front brake from a GS750 and a basket case pre unit 650 with trans with an extra set of cases, gear box case and the option of cast iron or alloy jugs. I need to figure out the rear tire, the gear ratio, carbs (thinking going balls-out twin AMAL GP's which will require a different cylinder head) Lucas competition mag and an assortment of engine mods and tuning to make it a road racer aka high compression pistons, race valves and springs race cams etc.... basically anything to make this run well at high speeds. This bike will NOT be a daily rider, but more of a street legal competition bike that eventually will see the track. I need to figure out the rear brake situation. I see a lot of people using conical brakes of OIF Triumphs or BSA's, and some using Norton Commando brakes. I know manx brakes and other super rare and expensive braking systems would be awesome, but short of a really great bargain find, I doubt I'll drop that kind of dough on the rear brake. Something later will be fine with me I have a rear wheel thats period correct for this frame but with the mother of all front brakes, the rear brake I have seems wimpy. As far as styling - I guess it'll all depend on what type of tank I can track down. I could go for a beefed up Goldie look, or more of a Manx style like the botton bike - though I'd probably use a manx seat at that point. The trim is the last thing on my mind right now. I want  performance!

Any advice?