If you wind up with .050" piston to head clearance, (.070" head gasket minus .020" pop-up, or positive deck height) that's about ideal as far as getting good squish, and insuring that there won't be contact when the engine is hot and the rods and pistons "grow" a bit. One can go as tight as .030" if your measurements are absolutely accurate and correct. Otherwise .050" is the general rule and more safe.
As mentioned you should be okay on valve to head clearence...but easy to check. Airflow around the valves is best with generous clearence between valve and head, but thats' a minor detail...not hitting the head is more important...obviously. !!!
Good luck.
Edit: I forgot to mention, anything larger than .050" between the piston and head at TDC will increase the engine's tendency to "ping" or detonate quite dramatically, as that gap enlarges beyond .050". Or...the larger that gap, the lower the compression will need to be, and the less timing advance that can be used. I hope that made sense. !!!
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Lumpy's post in 55 plymouth 230 engine block was marked as the answer