ryan, I have a complete a/c unit (the main housing assembly w/ evap & heater cores & blower motor) from my wrecked M50 1995 525i I took the A/C unit out as a complete deal and it's sitting here in my work shop. Tell me exactly what to take digital shots of and I'll send them your way, if it will help.
I was under the impression that the heater cores were the same in these vehicles, as long as it was the 525, 535 models w/ the IHKR II or III systems. Thought the differences came into play with the V-8 having the IHKA system.... Let me know and I'll do what I can.
1991 535i 176k (under serious surgery: repaint, interior swap, manual conversion, etc.)
1993 750iL 132k