You'll need a new program EEPROM for the computer that will shift the transmission according to the diesel shift schedules. Your 454 has a TPS (Throttle Position Switch) that can be retrofitted onto the 6.5, but I'd rather use the genuine 1992-93 6.5 diesel TPS. Just splice in the wires.

Most of the mass of wires won't be used if you install a mechanically injected 6.5, which would make the conversion a whole lot easier.

Jim