How not to be seen
The B-Bodies I have ran from 1977 to 1990 and share chassis parts with the '91 through '96 year cars. The BBC motor drops in with Chevelle headers, and Camaro headers on the SBC, though once again Chevelle headers will fit (I chose them to keep it smog legal as there was talk of inspections for large metropolitan areas, and the Camaro headers had air pump fittings).
I had to reinforce the frame on the upper drivers side as it was pulling the chassis side stock four link mounting point out of the body. I replaced the 8.5" 10 bolt, with a 1971 12 bolt out of a Chevelle running a 4.56 Richmond gear with Eaton posi and still spin the slicks.
Went through three built HD 700R4 trany's before settling on a 4L80 E. I would recommend going with a TH400 and a gear vendor as it costs about the same but there are more HD parts and goodies for the TH400.
As a ZZ502 it ran on the street for three years, with A/C off a '72 Chevelle. Though I had to use a Griffin aluminum radiator and a HD trans cooler for the 3400 street fighter lock-up torque converter. Great fun, stomped every body, and every thing around except the fastest Camaros and Firebirds, and they always ask for a rerun at the next light as I took them on the "top end" first time around.
Tore the "six quart" truck pan off the engine cruising down the interstate one night, so while I had the 502 apart I replaced the pan. Then the cam and lifters, then the heads, then the intake, carb and finally stuffed a 4.375' crank after boring the block out to a paper thin 4.60" which required hard-block along with new pistons and rods. I kept the 502 decals though.