with 220-230 grain pills in the 300rum I'd go with rl33 and start at about 90... work up to 95-100... The top seems to be rather rifle dependent as I am at 95gr with 225 hdy bullets at 3,000 fps and most using the berger 230 are at between 96 and 100 grains to get around 3,000 fps. Some are pushing a bit harder for around 3,100 fps but I don't push my rifles so I haven't gone there.
If you want to work with rl50 or h50bmg you will need to start at 95gr with a ~220 grain bullet and go up.... likely you will run out of case capacity around 100-102 grains for rl50. You should be around 3,000 fps also. I haven't tossed h50bmg downrange but have used 5010 (the mil-surp. that h50bmg replaced) and I'm sure it would work well too.