As the title states, I'm looking for a good powder and projectile combo for a 16" 6.5CM bolt I'm building.

I have several hundred pieces of Lapua SRP brass and CCI 41's.

I have tons of H4350 and 8208. Only have a couple pounds of Varget so would like to avoid using it if possible since I'm unlikely to find more anytime soon.

For projectiles I have a bunch of 107smk, 107tmk, and 142smk.

This particular load will be for shooting steel. My home range has steel out to 500. But, I can easily get to 1300 at a friend's place that's about an hour away. Range trips are 2:1 in favor of my home range.

Would shooting a lighter 107 grain bullet with a powder that's fast for the cartridge like 8208 work well in a short barrel like this?

You have good stuff to work with, but there is no free lunch at 1300 yards.

The Varget and H4350 tend to do better from the middle to the heavier ends, but all three Varget, H4350 and 8208XBR are flexible to some degree if you are only shooting 500.

Things start to need to look better in the tune department if you expect to perform at <1/2 MOA at distances beyond 600 yards, so you will need to work up your loads.

Try the H4350 with the heavier bullet find your velocity node and tune the group shape with your seating depth.

Try the lighter ones for blasting plates at <500 yards.