Lots of options.... 390's are a very good engine IMO. Check for a casting number on the block above the starter pad....

We have some very sharp FE guys on CHR, Barry and FFR to name a couple of them. Both are also very good at helping you with the casting numbers and helping select the right parts for a rebuild... Barry also sells parts at Survival Motorsports---good stuff.

My suggestion would be to get the engine out and apart, get all your block and head numbers, and decide how you want to build it... figure out your parts list, or buy a pre built short block and aftermarket heads... Kind of depends on your budget and how much horse pressure you want.

As with most any project on a car or anything else, Plan your Work, Work you Plan!!!