On most as cast, iron sbc heads anything over a 1.52 rocker and the push rods will deflect off the inside of the pushrod hole in the head. Clearencing is needed to fix this.
Buying the Cranes isn't so bad cause you'll have them for the next motor...
1.5's or 1.6's, depends if you want the extra lift...Will you have enough piston to valve clearence in this motor, will you want to buy different push rods if needed to correct geometry? Self allign or guide plate, are you putting screw in studs in these heads? if so no biggy it will all transfer to the next motor...if the next motor is going to be much more powerfull 7/16 studs may be what you want now...if not 3/8 will do just fine....Food for thought
