Maybe I mis-understood you're question. Were you asking about regular 45LC pressure/power loads in your 454 brass or were you looking at doing some considerable reduced loads (by 45LC standards) in the 454 brass? Regular 45LC pressure loadings will work fine in the 454 brass, I wouldn't put a heavy crimp on them tho. But if you are talking about loading "below the 45LC charts" in 454 brass, then yeah you could run into problems.

More power is like boobs and money, never heard anyone complain about havin to much of either!
HL