It does not matter if its a 350 or 383. The heads and cam have to go.
if this motor (that is probabily a 350) has a dished piston you want a 58 to 64cc head. Small 58cc is prefered to get the compression ratio up.
Install that new cylinder head with a thin .015" head gasket felpro 1094 to max the engine compression ratio.
Now you can cam it. A big cam will need a high stall converter and higher rear gears.
So if you are not going to change that, don't go nuts on the camshaft.
you can get a good idea of the cam by measureing the cam lobe lift off the pushrod, using a dial indicator.
(its probabily a stock cam)