Moog K6411 problem solver bushings, set of 4 that you can probably get anywhere. Not expensive. Much better than stock, but won't break your wallet. About 26 bucks or so for all 4 on rockauto. Of course, you already ordered the UMI's so never mind. Harder durometer than stock, but then you won't have the squeak problems that a lot of aftermarket polys have.
I'm supposed to have couple dozen or so of the NOS Camaro 1LE bushings somewhere according to my parts list that fit G-bodies. (They use the same LCAs as G-bodies.) GM p/n 10164152. They're hard as brickbats compared to stock, but look like the stock mushy bushings. I bought up a buttload of them when I still had my 2002 Camaro SS and SLP was clearing them out.
I'm supposed to have couple dozen or so of the NOS Camaro 1LE bushings somewhere according to my parts list that fit G-bodies. (They use the same LCAs as G-bodies.) GM p/n 10164152. They're hard as brickbats compared to stock, but look like the stock mushy bushings. I bought up a buttload of them when I still had my 2002 Camaro SS and SLP was clearing them out.