'65 Galaxie Restore or Hot Rod

Agree with resto-mod. Full blown restoration will cost a small fortune and take forever, and it will still not be a numbers-matching car, and if it has no provenance, it won't be worth it. A full-blown hot rod or pro street build will also cost a small fortune and you will never recoup that cost. Amateur hot-rodders and pro-street builders routinely lose money when selling their cars with few exceptions. Resto-mod gives you the best of both worlds. Keep the big block 390, easy motor to build and tons of them out there, get a decent induction setup at any speed shop catalog, replace all of the suspension components especially if they're still original, try to do as much body work, priming and sanding on your own, then get it to a paint shop for a budget paint job. Keep the interior spartan since as you say, it's trashed. Unless you live in the southwest you won't find anything in a boneyard to help you, and restoration parts catalogs are outrageously expensive, so make do with what you have, dress up faded vinyl trim with vinyl paint, or do what pro-streeters do, gut their interiors in favor of aluminum panels or bare metal interiors.