Oh as for pistons and freshening up, do the compression check, pull the heads and check cylinder walls. If they are decent you can probably do a basic hone job, new rings and bearings and let it go. If it's in bad shape you will need to take to a machine shop, rebuild, etc. As for pistons I am not an expert here but what I have in my 355 and what a lot of people seem to use are Speed Pro TRW flat tops. With 64cc Vortec heads and the correct head gasket thickness you will push about 9.6:1- 10:1 compression ratio and still be able to run on pump gas. I probably wouldn't run over 10:1 compression and wouldn't go under 9:1 for sure. Raising the compression some will help in gaining some power as well.
I am not an engine expert like some of the guys here so this is all I will say and this is all based on my opinion and what I have learned personally and from the guys here.
Good luck on the build!