Any GM engine will fit in your car without frame work.You would just have to relocate the motor mount perches on the frame and the holes should already be there.You may have to install heavier front springs and change things like hoses and the radiator.You may have to move the battery to the other side of the car but its pretty easy also.I would suggest a Buick 350 or 455 to make it as easy as possible.There are many possibilities a Chevy engine would be the cheapest if you plan to build the engine up for power because parts are quite plentiful for them.If this helps please click on my accept button.