I have a 92 RM and I have been booged with the same question. I can't answer yours though but if you are looking for a TBI spacer I found one through Oriellys auto parts store. The part is made by Airaid and it probably can be found cheeper than the 119 dollars that the auto parts store wants.
You can make one yourself. First you will need an airbox off a TBI Cadillac motor.
Donor cars to look for:
^^Some of these have the Northstar and it won't have this air box if it does.^^
You will need everything pictured, including the mounting stud.
Your existing b-body air box is held down with two studs. Remove them from the TB and separate the two pieces. Reinstall the bottom bolts. Now, screw in your new offset stud from the Cadillac
Once you have that you are going to need a length of PVC pipe for it. It should be 3" in diameter. You can get this from Home Depot. You also need a 45 degree elbow. You will have to put a hole in the side of the air box for the intake air temp sensor (passenger side). You will also need to install a small breather filter into the valve cover where the hose comes out and goes to the original air box.
It should look something like this.
It adds a great throttle sound and may help performance a bit.
Ok i love the ingunity of that its pretty good. However please do not use PVC i know its easy and cheap but look into exhaust tubing. and painting it with high temp paint. The reason is PVC traps heat and does the exact oppsiote of cold air it heats the air comming through the tube. A piece of exhaust tubing will also get hot but it wont hold it in and the high temp engine paint acts as a small heat barrier
I only say this casue ive done the PVC thing over and over again it took a while to figure what was happening ohh by the way powder coating the steel works best in case you wanted to know.