remove all the old sensors from your motor and put them on the 91. swap the manifolds, just use the head and block assembly. you SHOULD swap bell housings on the trans. the 91 has a hole in the top for a sensor you don't need. don't want anything to fall in. saw it happen on a benz once.

the opportunity to reseal the trans and replace the heater hoses, timing belt, seals, motor mounts, oil separator, man, i could go on. alot of things could, and probably should, be done also. and, use your flywheel and sell the 91 1. it has a ring for the sensor to read that you don't need. might help recoup the funds. good luck, chuck.