It is quite possible his 93 has a 16 valve motor. So they'd be of the same size, if so.
However, the issue he's going to run into is the fact that a 97 is OBDII (the emissions/computer system), so yes, he'll have to change out the wire harness. Or, I guess that if he takes the intake off the 97, and puts it on the 93, that everything might work.