Unsure Frank, much of the pump internals rely on diesel as a lubricant, there may be some leak off running through there?
There was an article I read many years ago, it was about certain diesels (not necessarily 80's ), having pump damage from having the thrust faces of the lift pump internals damaged by additional pressure from an external pump. Yet to see any physical evidence of this though. Without doubt it is an advantage to get rid of the primer head, and as per Chris perhaps have additional filters. I think the three OE ones already fitted are sufficient for my use, I do miss the little glass or plastic 'sight bowls' of yesteryear though.
Regards
Dave