Need some advice on some cylinder head gaskets

Magnum deck height is 9.58 vs 9.6 for La, and those pistons are zero deck if it hasn’t been decked(This part is new to me so I could be wrong). 58cc heads and .039(1008) gaskets puts you at 10.5:1 compression.

I would agree on thicker gaskets, but you do need to consider the pistons as a possible weak point. Some piston dishes are just cnc’d Leaving them fairly thin:

Self Tuning Pistons (new marketing idea)...

Might also be wise to start learning about water/meth injection.