A cutlass,a chevelle,a grand prix and a transam, but haven't done a square body.Yet! But all of them were easy peasy.The reason for the bastard swaps I was young and broke,all done from age15-25.Like the cutlass it had and needed a olds 350 found a whole cheap pontiac big block wagon, pulled the engine and trans dropped it in accessories, trans mission, pontiac frame mounts. Non of them were hard.Think about it as example, GM A body line( Skylark,Cutlass,Chevelle,Grand Prix) all the same frames but different engines in each.All those engines are very similiar in dimensions and mount locations that's why GM could use the same frame for all 4.Only thing special was re routing wiring , and hoses and some times have a driveshaft shortened.Ive since learned how to shorten them .FWIW a friend had a 455 Buick in a c10 my GM swaps BB pontiac to Cutlass, 455 Buick to Trans Am,350 Chevy to Grand Prix,455 Olds to Chevelle.All on factory mounts factory oil pans etc. If I was building a Mud Truck I do a 455 Buick in a Heart beat they are light as a sbc and torque for days.I worked with a guy did a 500 Caddy to C10 it was more of a Pita because the interchangeable parts weren't there.Tom had to order or search for everything.