1963 vintage, Williams FP with Firesight. It'll get the job done every time.
I put a scope on my Marlin 336 and shot groups with different brand ammo and bullet weight to see what it prefers then put a Williams FP and front Firesight on it. I did pretty well with groups at 50 and 75 yards, 100 yards just OK and 150 yards not so good. I realize that if I stay with the iron sight there needs to be a lot of practice sessions.