[Barry_R]

Mixed messages. The short block you describe is very economy oriented and would be well served with any decent bolt on alloy heads beyond the unusable Pro-Comp stuff. You would likely never know the difference between a RHS or an Edelbrock street head at that level - without porting, other things would be holding it back.

The largest AFR head I would use on that would be the 185. We've run those often on 331/347 combos and had them perform really well. On a recent 331 with AFR185s, a hydraulic roller and an Edelbrock dual plane we got right around 400HP/400TQ running an ancient but much modified 715 carb. Fit nicely under a flat hood '68 Mustang. The 306 would be on the good end of the fringe with a similar combination - not quite as crisp due to port volumes with less TQ and similar peak power.