Years ago,my older brother had a '69 Camaro that had a healthy small block in it--he replaced the oil pan that was rusty and dented with a ribbed aluminum Mr.Gasket one thart he bought at a swap meet for 20 bucks--after a few months he started noticing a piston slap noise when it was started up cold,and a vibration also started in,and got progressively worse,till one day he decided to pull the motor up off the mounts and pull the oil pan to see what was going on--it turned out some baffles in the oil pan had busted off,and gotten tossed around in the crankcase,and peices of it broke the piston skirts on 2 pistons,and some got into the oil pump and timing gears!...he put a stock oil pan back on it after repairing the damage and swore he'd never again use a "Mr.Gasket" oil pan....he thought aluminum would be a good choise as it will not rust,but I have seen a few corrode so badly they leaked just as bad as a steel pan too...
My friend replaces quite a few rotted oil pans,gas tanks and radiators,Spectra brand aftermarket ones are pretty good quality,a lot cheaper than OEM and they have pretty good selection of different ones for popular vehicles..