A B4U/FE3 car should have had the same bars as a 9C1 or Impala SS. Front is 30mm (1.18"), rear is 26mm (about 1"), best I recall.
An FE1 car would have had a 28mm front bar and no rear bar--that's just a little bit over an inch in diameter.
These parts bolt on, so whoever you got the car from either removed whatever was there before, or didn't know themselves that the bars were missing. I'd guess that a previous owner had a set of good bars on the car that were sold off to someone else before the car was sold, since they were worth more sold separately than with the car.
Since you are on a budget, suggest you find a set of stock Impala SS bars--there are plenty around--and use some Energy Suspension greaseable front polyurethane bar-to-frame bushings, and poly end links. Use Energy PN 3.5183 for the frame bushings, and 9.8123 for the end links. There are a number of other end link sources, both GM and aftermarket.
If you don't have mounting hardware for the bars, let us know--or search the Forum as there are plenty of threads about this. I would not try to make Camaro bushings work on the Impala or whatever bar you have or end up with--the bushings are fiberglas-lined for smoother action/less friction.