Just rebuild that short block with a better camshaft and then just get a set of Edelbrock heads out of the box because you can not rebuild the steel heads right for the money you can buy the Edelbrocks for. Then get an Edelbrock Performer RPM intake for the top end. You can do a nice hydraulic flat tappet if you use the right break in
oil and then keep running something like the Jo Gibbs Hot Rod
oil that still has the
zinc and other additives to help it live. You will then need a nice carburetor and distributor as well. You will spend in the 5000.00 to 6000.00 range depending on how much you do your self and exactly what parts you use. You should be able to get in the 450 to 475 HP range out of the engine depending on a few things that you do. I can build you a complete 390 if you would like for about 8000.00 that would do you a nice job and have some nice parts in it. Good luck, Keith Craft