2 powders for 6ARC and 6.5CM ?

[Bassfish1952]

I shoot both, kind of in the same boat as you are.
If you only want one powder for the 6.5 Creed, then H4350 is your game. I'm finding I saty in the h4350 world more and more, so others are on reserve.  I4350 is not the same, period. So no sense even asking.  I was gifted 6# and frankly it just sits on my shelf.
I shoot 100 ttsx, 120's both gmx/ttsx as well as the nosler 120's, 130's a lot 3 flavors, 140-143's some but more often than not, the 130 class.
My second most used CM powder, for me, is Varget, primarily for 130 and below class bullets.
So if you wanted 1 powder for the Creed and the 6Arc, and can stand for the lower velocity in 6Arc and possibly the Creed, then look at Varget for that, but you give up a lot so why do it.

Honestly, though, Lever will do most of the work for you in the Arc and H4350 for the big boy.

There's your 2, lever and H4350.  There is a lot of difference in the burn requirements of these 2 calibers that makes 2 powders for both all the time, hard to do. 
If you only want 2 in your cabinet, then pick 1 good one for each like the above.
H4350 is available again, so its not a problem to find.
If either becomes scarce, then there are alternates you can look at for either, when the time comes.  Like in the scam-demic unpleasantness, H4350 was scarce as hen's teeth (as were many), but there were alternates so I could keep going.

Other thing about Lever and the Arc, you don't need much powder due to small case size, so each pound goes a long way.

Biggest help you can do for yourself is to buy 2-3 lbs minimum of the same lot#, for each powder.  Here in the real world, a change of lot# for a given powder will affect your MV, sometimes by a lot sometimes only a little.  You can of course adjust for it by shooting your old lot# weight with the newer lot over a chrony and tweak, but having it all in 1 lot# saves you time and effort.

So when I restock, I don't just buy 1#, I get 2, 3, or 4 depending on my budget.
Do plan ahead and keep some reserve on  your shelf.  In today's wack-o political time, scarcity will be a recurring event.

Thanks for the reply . Right now I just have 1# of LR to play with but like it  Probably will get an 8# next and with what I shoot that will be my lifetime. Same with the 6.5 I'll try a pound and if I like it get 8# and go for it. 
I think I was told before powder is good for 10 to 15 years if stored right. So 72 - 87 don't think I have to worry past that.