I'd find some 915 heads & build for .040" quench (piston to head) for a MUCH more efficient eng (torque/mileage/power). 8 blade water pump with an added anticav plate. Possibly a VS rather than a DP carb & if a Holley get one of the holley clones with adjustable air bleeds

live every 24 hour block of time like it's your last day on earth