[dscott]

The first thing to check is the frame to make sure a big block will fit. Classic has a small and a big block frame. The small block frame has a metal floor pan on the drivers side footwell. The big block frame has a fiberglass foot box. The change can be done without to much trouble. You will need to change the front springs, Radiator and fan depending on the hp of the engine and which combo you have now. Headers, frame mounts, motor mounts, trans mount, driveshaft length. The trans will work if you install a scattershield. The steering shaft may also need to be alterered for header clearance. The wiring is the same, shifter location may be slightly different. It sounds like more work than it is. Let me know if you proceed I can help with part #'s etc.
Don