Hi @WipedFilmGuy
Deep vacuum and triclamp parts never worked well for me, as you mentioned they leak and are mostly designed for positive pressure. I imagine the solid Teflon gasket was the way to go.Have you tried using kf flanges instead of the triclamp parts? In my opinion they are more suited to the high vacuum applications, they also don’t require monstrous torque to seal.Lubricants can be used on threads but it is important to understand how these effect torque spec, the proper considerations must be applied when using that method.
Lastly brass nuts used on a stainless steel bolt will not cause galling, only a stainless bolt and nut combo will result in that. A you will know they are galled when you need a cutoff wheel to zip the bolts in half to remove the clamp. We had an issue with a local supplyer a few weeks ago, their entire shipment of high pressure triclamps came with a bolt and nut combo that was too short to be used in conjunction with the clamp, we were on a tight schedule to start pressure testing parts and used some fastners we had in house… all stainless 
had to cut the dang things off , one for each use…In that case a lubricant like anitseize or the dry ptfe lube you suggested would work to prevent galling, but only SS on SS or like materials such as AL on AL.