Switching from 18 inch to 20 inch 308 and OBT

[Maukings]

Hoping someone can illuminate me. I have an 18 inch 308 barrel that is shooting 168gn bullets at 2600fps with 43.4gns of Varget. This puts it on the 5th node at 0.9245 OBT. This same load on a 20 inch barrel gains about 60fps but it's now too fast for its respective 5th node and too slow for the 4th node. In order to take advantage of the added speed you get from a 20 inch barrel, i'd have to hit the 4th node with 45.7gns of Varget. Has anyone loaded 308 which this much powder? Is it over pressured?

I'd hate to spend the money to get a 20 inch barrel which will end up shooting slower in order to keep it within the safe pressure node because the next one up is too high.

Thanks.