I ALWAYS started w/IMR4350 for ALL 70-100s in 243s and have had great accuracy and speed. Admittingly, there is likely more speed to be had w/100s w/slower powders. And with the lighter slugs like 70 I had used Varget to good effect.
My 85 X load was the same as my Sierra GK BTHP load, max w/IMR4350, netted only 3100, but out of a 20" tube. Good, not great, but plenty for a nice hog at 240 yds, DRT
I would feel the 4064, 4320, and Varget would get a nod for common powders if you want to milk top speeds and why not if they shoot well.
Sure you will find a load quickly, seating depth seems to be a key often with Barnes, but never heard a bad report on that 80 TTSX.
You should have much success, at the range and field. FWIW, my rifles showed a preference towards Federal and WW cases over RP for the best of accuracy.