[DanEC]

A true CJ motor is a pretty nice motor and yes, the restoration examples I saw at Keith Crafts shop were pulling down about 410 HP stock according to the dyno operator. You might consider a set of Edelbrock heads and just put your original CJ heads away someplace safe. Fairly easy bolt on change.

My heads are 1961 390 HP heads (as in 390/401 HP) that Keith Craft ported and put larger valves in. They are very close to the same as your heads now except for maybe a little additional porting. I asked the dyno operator how much additional HP my engine might have made had I gone with Edelbrock heads and he guesstimated about 30 - 35 HP based on his experience.

Something to consider.