You've got a lot to consider here. As it is a lot of work to do. I'm
sure others might of tackled quite a project. I know a few advised
against it a year ago when somebody posted the same question.
Things you need to check out.
1. Are the seat anchor studs spacing the same on a car with a bench seat
vs. a car with bucket seats?
Are you replacing a manual bench with power buckets? You'll need power
seat wiring harnesses too, The carpet has to be removed, this requires
removing all the trim around the carpet and door jambs. Careful with the
all that old brittle plastic it breaks very easy.
2. Seat belt anchor points might also be different. On the drivers side
of the bench seat the anchor point for the belt connector is within the
seat frame. Is it the same for the bucket? Or is it anchored in the
floor? If so, your car won't have the anchor in the floor.
3. If your looking in salvage yards for parts, can you find a decent set
of seats and a complete console in the color you want? I doubt you will
find any new console parts through GM. Interior parts are the first
parts that are deleted from stock when the car gets old. Your not
thinking of adding Cutlass parts are you?
They are different than GP parts.
At least with a 1990 you don't have air bags equipped seats to deal
4. A bench seat vehicle may not have the console anchor brackets in the
floor. You would have to add these, plus the shifter mechanism, get it
lined up properly and punch a a big hole in the floor for the cable
routing. You might also need to change some exterior brackets for the
shifter linkage on the transmission. You'll also need to do some
electrical wiring for the console lights / gear shift indicator light.
5. Are you also going to remove your column shift steering column too?
That would be an added cost to switch columns, although I don't think
its necessary, you can just remove the shift lever.
6. What condition is the car in? How many miles? Is the car really
worth all this extra work you plan to do to it? If your only going to
keep it, say 2 more years it won't add to the value of the vehicle.
7. You might also consider buying a car already equipped with buckets
seats & a console.
I've done some seat swaps in my day, some were easy and direct bolt-ins
and other cars were pretty much cut & paste.