2 threads gap on the buffer tube is right.
Regards to the bad lever... I don’t like the idea of them at all. In terms of the MWS, you’re adding weight to the bolt stop assembly. The ZET plate will have to lift that extra weight, which will effect bolt lock performance. Having bled profusely for hours after a Scar H bolt bit me, I don’t want any extra ‘help’ releasing the bolt when I don’t want it to.