First trouble will be that you won't be able to put that B4 ACE engine in a B3 saloon without welding, because engine blocks are different and you won't be able to bolt to ACE engine mounts of your existing engine - because B3 A80 has engine mounted on subframe, while B4 has all engines mounted on chassis. Solutions 1) substituting 6A/9A engine for ACE 2) drilling off mounts from B4 and weld them to B3 chassis and either swap subframe for B3 A90q subframe, or cut off engine mounts from existing subframe 3) custom made mounts, if local laws concerning custom mounts make this route feasible.
If you want it to be as simple as possible, then you should keep ACE's KE-motronic - because it's just swap of loom and related stuff, unlike your plan, which involves careful building of substitute loom - or, probably, making some electrical mess, depending of your skills. I didn't understand what do you want to use for fuel supply for your plan...
Steering rack should fit, as for the rest - you should get crank pulley from B3 with both AC and PAS [yeah, tough thing, I know
] and probably mounts for B3 PAS pump.