ProComp/Speedmaster aluminum heads

The 596 heads are in perfect working order as they are. If anything ever were to go wrong with these aluminum heads I could just pop those back on. Of course if it doesn't take out my bottom end LOL...
596 isn't that a tractor head. lol I'd swap the springs as the Crower are a known quantity, the others aren't even after checked.
probably make a good spring for the tractor head. lol