Nowadays it seems the popular V8 swap into our cars is the Vortec swap and if your planning on keeping a standard shift the transmission of choice is the T56 . The T5 that comes with the 8 cylinder cars , even the so called "world class" T5 , is a weak spot that fails miserably with any kind of increase of the factory stock power level , you can read about all this and more at ThirdGen.Org under the subpage "Engine swaps" (the "power adders" section is kinda fun too , turbos , nitrous , ect) .
Fun Fact ; Look up the 1989 20th anniversary Turbo Trans Am (TTA) , the fastest American built car in 1989 . They built and sold around 1500 of them with the 3.8 Buick/Olds turbocharged V6 and had the Chevy execs crying foul (How could the lowly Firebird be allowed to be faster than their V8 Corvette ?) .
If you decide to stay with the V6 it's quite popular to take a later model 3.4 (RWD) engine , turbocharge it up to around 300 HP or so , and then have some power to go with your cornering
