Looking for Solid Parts Car

I've got a 1980 El Camino still backing the factory Saginaw four speed. It no longer has the LG4 305 but is packing a mild 350 Chevy. The body on the outside isn't too rotten. It has another frame under it, but the worst part is the floorpans. On the drivers side they're rotten from the firewall back, on the passenger side they're good until you look behind the seat. Repop floor pans are atleast $460-$550, something I can't afford right now.