Probably your engine block was line bored and causes chain to be looser. I have used cloyes true roller chains always nice and snug. My 360 is a virgin non line honed/bored block. When I took it to machine shop to rebore cylinders they wanted to line hone. I refused! When we tore down block mains were nice and true. Crank spun freely no wear at all. Still went ahead and bought all main and rod bearings new.
