Brutally honest? Wrong caliber, wrong rifle. If you are doing it just to do it, don't let my opinion stand in your way.
Load up 50 rounds of 175 Sierra's (or 165 Barnes with your powder charge)to max velocity in your 300 Weatherby, then shoot them all in 50 minutes or so. Convince yourself that it was fun, then load up 50 for your 243 and do it again. I'll bet the 243 is plenty accurate enough and a lot more fun.
You ask for advice elsewhere on this forum, then ignore that advice. You know what you want to do, so just do it.
I am interested in your after action reports though, no matter what you choose to shoot.
Regards
(BTW, do you have a 427 1969 Vette?) I gotta know......