If my memory is correct, it was the H&R revolvers chambered in .32 H&R Mag that were the reason manufactuers largely loaded .32 Magnum ammunition below maximum because the H&R guns couldn't take them.
Buffalo Bore says on their website that their .32 Magnum ammunition that they advertise as +P is safe to use in any .32 Magnum revolver, EXCEPT the H&R revolvers.
If even the 5 shot H&R R73 Buffalo Bore says .32 Mag isn't safe in, then the 6 shot 733 or 633 it would not be safe. Especially given the age of them and goodness knows what type of wear they've seen the past 30, 40, 50 years.