Police engines in late 70s had special cast cranks, got one, but my 74 cast crank engine was running 7.70s in my 64 Plym for a year or more before I changed to the steel crank engine. The 74 engine is now going in my Lil Red, maybe 15,000 miles on it. 5500 and both are done up top so that helps a lot, anything will break but I doubt you’ll have a problem
btw mopar stocker racers search out for the cast cranks to run in their engines, lighter. 340s (use 318), 383s, 400s and 440s