[steve25]

There are many very important things is confirm long before fretting about cooling!

1) that the valve notches in those pistons match the valve inclination angle of those 59 heads.

They look like they do since they are so removed from the center of the piston,

2) with the dish milled into those pistons you need to find out how much thickness is left in the tops and if that’s enough meat to live with the amount of boost your likely to ever run.

3) what rods are in the motor.

4) what valve springs are on the heads and if the intake valve spring has been set up to still be able to close with the max boost you ever intend to run.

For example, if your intake valve size is 2.02” that on average makes for 2.73 sq in of valve surface area. With just running 10 lbs of boost you will need 30 more psi of seat pressure then if the motor was not supercharged.

I would also want to know what brand bearings are in the motor and the clearance’s.

I would want to know how much valve to piston clearance I have without a head gasket in place.

I would want to know what type of steel the exh valves are made of.

I would want to know if the two compression rings where Moly face or not.

I would get a flow test done on the heads to determine there intake to exh ratio.
Also from your photo’s I can’t tell if the heads have the needed push rod guide plates installed?

I would also drill the extra cooling holes in the center deck area of the 400 block to match the head gasket and then opposite those holes drill the head gasket and then of course the block deck and the heads, so 4 holes total are added for better Cooling of the center exh port area can be had.

In short you need to dive into this with the frame of mind that the motor was built by a idiot until proved otherwise!