i dont know what the weight difference is between a 97 rcsb but the 5.3 liter in my 04 rcsb isnt very impressive. ive installed the lpe gt2-3 cam and have had 3 differnt tunes by allen nelson but i just dont think the cubes are there for fun perfomance. id go 6.0 for sure. save your $ and go with it. more cylinder head chocies also.