You're on the right track. I haven't used any of the new powders, but LC match or N/M brass with Fed 210M primers, 41.5 gr 4064 and a 168 gr Smkhp was my load (and a lot of other shooters) for M1A's when I was shooting gas guns.
If you get a chance, try some of the LC M852 N/M ammo. It was as good as (or better than) my handloads. I think it was loaded with 4895. Also, if you can find some of the Federal Match that came in red boxes, it was on a par with the M 852 LC. I don't think that the Fed Gold Medal Match is as good as the red box was. Don't know why.
Enjoy; M1A's are fine rifles. Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time