i have a 1998 318is that has a shite motor, to which is also blown

im buying a complete 1991 325i to use as a donor car as the shell is rotted.
both cars are manual

im wondering aside from a straight bolt in swap, what do i need to look into for the electrical side? going from an obd2 shell to obd1 heart. or will it basically be plug and play with some security deletes?

cheers!!