Try Hodgdon.com and their "Reloading Center". Hodgdon/IMR/ and Winchester are now owned by the same group.
The Lee manual lists a starting charge of 46.2 grains of 748 and a maximum of 48 grains for about 2850 fps.
BTW: With few exceptions, it doesn't matter whether it's a Sierra, Nosler, Speer or Barnes, or ???? make of bullet. A 150 grain bullet is a 150 grain bullet. This is the reason I gave up on reloading manuals made by bullet makers; Too limited in their scope. JMHO. ~Muir