Im sorry but when you say hot rodding it are you reffering to shooting fast or shooting fast loads?
To me, that means squeezing every last bit of velocity out of it right up to the unsafe pressure point.
If I were you, 300RUM gets the nod, but I would urge you to look at other rounds than the 30 cal. Look that the 7 RUM and the 338 RUM and others like them. Compare real life speeds/bullets on JBM ballistics
from these chamberings and weigh the benefits with the obscurity of the rounds and see which are the most important categories you will be willing to sacrifice other categories for.
Michael said it best when he said, "More BC and trigger time." That's the way I see things- if you are in perfectly still conditions all the time, BC isn't as big of a factor, but if the wind is 10mph full value, there is a HUGE difference at range between a 150g bullet fired from a .308 and a 300g bullet from a 338AM and certain bullets/chamberings give you a higher percentage of hitting your target than others. Even more so if the wind is 25mph. Do a little research on these different rounds on JBM's website and decide what you want. Personally, a .243AI with 1:7 twist shooting 117g Matrix Ballistics bullets, and a 338RUM battery is perfect for me, for now. Eventually, add a .375Allen Magnum and some other junk, you know how it goes.
Good luck with whatever you choose.