Q shorty stock & 8.6 blk

Hey Y’all, I’m planning out a 12.5” 8.6 blk upper for use on my (soon to be SBR’d) ar10 lower. It currently has a 16” 308 upper with a bleed off gas block. The 8.6 upper will also get a superlative bleed off gas block.

I want to put on a Q shorty stock but I cannot figure out how to configure the weight/spring so it will work with both uppers. The only options are 3 oz or 8oz. 3 seems small and 8 seems too large.

Does anyone have any suggestions?