OBDI cars are easier to mod. They are the pre 95 models, the 325is in your case. the 328is is 96 and later and is OBDII. Im not sure which years have the least recalls, but a 95 or 98 are the years I would look at. 95s have all the early problems worked out but are still OBDI and mod-freindly. The 98 will have all the OBDII bugs worked out and most likely the lowest mileage.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>