well its pretty easy to put a t series engine into a ke70. just get a wrecked t18 for its engine xmember and the t50 gearbox and all other bits you want. i put the pedal box, hydraulic clutch. etc into mine. i am only using a 3tc. if you are using the twin carbies on the 2tg i hear they will hit on the brake master cyl etc.
as far as the earlier rollas go i am unsure of the mods needed to the xmember and other things!