what is the difference between a buick long block 3.8 and a longblock 3.8 for a buick regal grand national?

Question

want engine swap w/o changing displacement

Answer 1

There should be no differences in the size, shape, or bolting of these two motors. The differences will lie in the compression ratio, camshaft lobe lift, and possibly the size of the valves. Since the GN is a turbocharged motor, it will have a lower comp ratio, but will most likely have a more agressive cam lift and the associated size of valves will be bigger.