318 to 360
Cole, do you have the 360 now?
The KB107 pistons are good to use. They will give you a 9.8-1 ratio with a .039 thick gasket and normal 360 heads which are open chambered.
The Edelbrock intake is a gem.
Exhaust manifolds or headers?
A Mangum head swap requires the hollow pushrods and you will have to recalculate the cams lift due to the 1.6 ratio like this;
Cam lift / rocker ratio X new rocker ratio = new lift
>500 / 1.5 X 1.6 = new lift at valve. Math looks like;
.500/1.5 = .33333333333333
.333 x 1.6 = .533
Your spring selection for the Magnum head should handle .533 lift.
Schmaucker creative services have the motor mounts you'll need and there a bit expensive. But wort it on the older sandwhich types since there blow proof/interlocking.