The first thing I can tell him is you don't really want "cheap".
I have seen far too many cheap rebuilt crate engines that had mixed up rods, pistons, parts installed wrong etc., etc..
Either go with a good reputable company's shortblock or build your own.
Just Google search 302 or 5.0 shortblocks or crate engines. You'll get lots of results, just choose carefully.
Here's one you could probably trust. LRS