I’d start with Varget & 4064.
Late last Summer a friend couldn’t find 243 ammo, asked if I’d reload him some. They had a little in stock at sgammo, but I told him I would. I 1st told him he’s not supposed to shoot another’s reloads.
I loaded up the Sierra 85 grain gameking, Varget powder. I also gave him other loads for practice. One shot & the 1st time hunter had an anterless deer down. Since it was a youth shooting, I kept the powder charge reasonable, COL to fit any chamber.