If you want to keep it simple...GO EFI!!

Once u sort out the computer...adjusting mixtures is as easy as pressing a button on a keyboard.
You A/F ratios are dispalyed etc....

L18's also seem to have all torque down low...but this can probably??? be changed by changing the exhaust/cam/carbys.

My final thought. Most engine conversions require roughly the same amount of time to do...so do an engine conversion thats worthwhile.