It also depends on the part. Bed sides and sheet metal won't matter much if you replace them with steel. Fiberglass fenders seem to be a death wish for some reason. I use them and really like that I can get replacements any time. The only number you need to worry about is the block, it has the VIN number on it and needs to match the title.
Internal engine pieces are wear items and anyone in the sales business knows that. Just look at some of the restored numbers matching muscle cars being sold. They have been rebuilt from ground up with almost all new parts, yet claim numbers maching all original.
Keep major parts like drivetrain, suspension, switches, seat, gauges, and steering. The rest can be replaced with out much care or looking.
Joe
