N540 would work. If you loading book doesn't give a certain powder you can always go to a burn rate chart and figure out very close to what you might need for a starting load. Which a few grains less the max load of a faster burning powder is safe. (less Pressure because it is slower burning.)
Powder Burn Rates
You need to read up on the bullet seating depth. Your .243 105 - 107 gr boat tailed hollow points are very long bullets compared to your 70 gr varmint bullet. So you have to figure out what max length the bullet can be seated out to just barely touch the barrel rifling lands when you jack the bolt all the way down.
You need a long cleaning rod or rod of some type in case you get the bullet left in the rifling when you jack the case out. You can also buy the bullet seating length tool.
Just seat the bullet way out when you first load it and you carefully jack the bullet in. If it touches stop and jack it out. Put it back in the seater with a couple more turns down on it and try again. You want to get to point where you see the probably 4 dings on the sloped edge of your bullet nose with the bolt fully closed. Now with a caliper measure the length of you bullet/case total length. Now write the figure in your reloading book notes for that 85 grain bullet. Pressure and accuracy is affected by how close the bullet is placed near the rifling lands
Now you need to test where the sweet spot is for your rifle. So load up 3-4 bullets with the loading seater turned down a thread or so and then caliper the round to make it .003 shorter than actually touching the lands. The 3-4 more rounds .006 shorter.......... Read up on bullet seating depth.
but anyway. Get your groups down small. Make good notes on seating depth for each type of bullet grain.
Only put one bullet in at a time. The recoil can dent the tips on any soft pointed bullet or maybe change the seating depth on hard nosed bullets. Always keep your bullets at the same temperature or testing goes out the window. Bullets sitting in the sun make more pressure when they are shot.