Unless you are doing major performance improvements you just need the correct new sample tube in the aftermarket MAF. I'm not sure about the very early SC's as they had a smaller MAF but generally 89-93 had 30lb injectors and the corresponding Mustang rated sample tube was a 19lb (and 24lb rating for the later 36 lb injectors on 94-95 SC's). A genuine supply source like SCP, MN12 or C&L will give you the right size tube for your car. For the Throttle Body, most recent upgraded models come with the proper bell crank, so it's a straight swop - you would be wise however, to port the intake plenum a little (using the gasket as a guide) and quite offen the TPS has to be re-adjusted, by rotating the body and using a simple volt meter to bring it just under 1v (like 0.98V) .