I can tune these cars, no problem. I use SCT software/hardware and can custom burn a chip for any application.
Vacuum sounds about normal for the cam you have depending on what rpm it's idling at. The 89 is a bit tricky to get to idle at times because the EEC on those years doesn't offer much control. The best thing you can do is increase airflow through the TB to get a base idle and go from there.
You also might want to consider that 38lb injectors are no where near big enough for whenever you get the motor running right.