N2TRKYS,
Dunno how you're working up loads, but if you check Hodgdon's pressure-tested data, the vast majority of the time max listed loads for H4350 and IMR4350 produce just about the same velocity, though there are exceptions. Here are some examples from Hodgdon in various cartridge/bullet combos I've used both powder in over the years:
.243 Winchester 100-grain:
H4350 2973 fps
IMR4350 2958 fps
.30-06 165-grain:
H4350 2781 fps
IMR4350 2770 fps
.338 Win. Magnum 250-grain:
H4350 2637
IMR4350 2634 fps
.375 H&H 300-grain:
H4350 2645 fps
IMR4350 2478 fps
