Plan of attack - 'Proper usable tune, minimal work needed - basically a reliable machine that can be produced from easily accessible items that work together.'
No welding, not massive transfers, 65% exhaust (could go to 70%!!) basically around two hours work in matching cylinder, packing plate and a little port work. No doubt I could get more pushing different areas but its just sweet and a nice ride to be honest!!

TS1 - 70mmx60mm
MB Piston
YAM Rod
OKO 30mm carb
Fat Mamba exhaust.
21.84HP peak (24hp'ish on such as Diablo's and others), 20HP+ for over 2000rpm and torque of something like 16lb/ft although don't have the graph, previously peaked in line with HP.

Blue curve prior to needle change and some carb mods.
With the SX box and 16x46 I can sit at 70mph at 6300rpm (19HP) with plenty left in the bag to pass vehicles etc and to take it to 80mph+.
Anyway no record breaker but is without doubt a proper road tune IMO.