4.3 to 5.7 computer question

i am doing an engine swap on a 94 silverado with a 4.3 and im giving it a 5.7l 350 from a 93 suburban. my question is can i use a computer from an 89 silverado that had a 350 because i have that computer lying around. Or am i safer off just going and getting a new PROM for a 94 with a 350 for my current computer.

Can you get the ecm from the burban? If not, I believe there is not any difference in the ecm for a 93 or a 94. So getting a prom should be ok as well.