Swapping HT4100 (4.1L V8) Fleetwood Brougham with a 5.7L V8

I have a 1985 Fleetwood Brougham RWD with a 4.1L and a THM200-4R transmission. However, it started leaking engine coolant. After inspection, it is somewhere from the back for the engine - very possibly engine block. I am looking to replace this engine. I found a 1990 Cadillac Brougham with a 5.7L engine. The 1990 model has an electronic speedometer, etc., and as far as I researched a THM700-4R transmission. Is it possible to swap the 5.7L engine into my 1985? Will it work with my current transmission, or will I have to include a transmission swap? I really appreciate advice.