Ant,
Some info that may be helpful with your build. 1 1/8″ headset, 26.6mm seatpost, 1 1/8 seat post clamp, and a 5 3/4″ profile spindle may be better to run than a 6″ spindle. I am using a 6″ spindle and it took alot of spacers etc. Andy from Chip & Dale should have the bottom bracket you are looking for as well as spacers. I bought a BB from him for $40.00 awhile ago at EHT. Good luck with the build. What color did you get? Any pics?
Paul