racinaround wrote:
Do you have access to an A13? I think that the longer stroke coupled with the small bore diameter would yield better torque in the RPM range that you are seeking to run in.

racinaround wrote: Other good suggestions that I have seen in this thread have been the 3.54:1 final drive and the 5-speed box to hold the revs down. The round port early A12 head with the quench chambers should yield a good compression ratio with reasonable pistons. Some of the things that make power also make an engine more efficient for the purposes of economy. Smoothing the short turn radius a bit (not polish as that will separate the fuel from the air mixture), a good valve job as cylinder filling will equate to less throttle position for a given power output to maintain speed. Good luck and keep us posted on the results.