IMR-4064 is where I would start and most likely end.
I shoot a lot of those 65 V Maxes in my 243s....
4064 of course...
44.5 to 45 grain charges, Regular large rifle primer...
for some reason, that charge with that powder, and those charge weight, seems to favor Federal LR primers....
don't ask me why, but that is in 5 different 243s... so I don't question it....
YMMV.
70 gr TNT is also a dandy bullet in the 243... and with the above charge...
will work dropping Blacktails just fine also.