[spacemanspif]

My sister had multiple v6 90s Camaros. I wish I had paid better attention to them when she did. She never got terrible mileage but can't give a number because she never checked MPG. Her's were all autos and may have been geared different than a manual. I'm not sure about 90s units but I know the 2000s ones with LS1s had something like a 3.23 rear gear, so they are already geared kind of tall unless the v6 got shorter gearing to try and make the v6 perform a little better off the line.

I think they are a good base, much like the Corvette is; both cars are quite sleek. Being rear drive, you should be able to put almost anything under the hood and with the use of a custom bell housing you should be able to keep all transmission related hardware stock.