Hmmm. Dunno about the 4895. What I do know is that some of the slow-burning pistol powders are quite usable in large rifle cartridges for reduced loads.
As a for instance, around 20 grains of 2400 in an '06 will push a 169-grain lead gas check at around 1,900 ft/sec, +/-. Per the book I used, a gas-check bullet can be pushed to around 2,400.
So, going by guesswork and extrapolation, you could probably use, say, 25 grains of 2400 behind that 150-grain bullet and get maybe 2,300-2,400; maybe more. I'd gues that the use of oatmeal or some such filler would give more uniform ignition.
It's one of those deals where you're just gonna have to start somewhere and tinker. Then you can write a book, "Reduced Loads for the 7mm Maggie" and get rich.