I've faced this same dilemma twice with my own cars, in the last few years. Once with a 69T and the other a 71T.
The decision was easy. Maintaining matching numbers being important, I chose what I call the 2450. 70.4 x 86mm.
The choice is easy because you get rid of the non-counter weighted crank and the 86mm cylinder slips into the case without machine work.
The formula I chose was 36mm intake port, 9.5:1 compression and a Mod "S" cam.
All told this formula creates a 180 RWHP rocket.
Easy to drive with the Mod "S" cam making hp as low as 2800 and 180hp@ 6400.
Super wide power band and incredibly fun to drive.
Cost, 2.4/2.7 crank, (relatively inexpensive), AA 86 MM (9.5:1 forged pistons) relatively inexpensive, porting is easy on these heads, and the expensive part is the billet cams.
The other option is the Mod Solex cams which can be ground on a set of stock "E: cams.
