Thank you Tabetha, that's a big help confirming what I kind of suspected.
You are correct. We have a lot more pressure than the standard system can cope with. I guess the higher lift cams I have fitted might have something to do with it as well, as well as the superior BOB inlet plenum we made to fit.
With inlet, do you mean the actual airinlet to the heads or do you mean the inlet for the venting system (what I described I want to fit into the sump)
The outlets will be on the back of the camcovers practically against the scuttlepanel and will be the highest point in the engine. I'd say the fact warm air goes up and cold goes down this will help venting the engine, am I right?
The standard PCV would not only fuel but the air as well. That's one of the reasons I am in 2 minds about PCV to inlet. When tuning that's not what you'd want. Foul warm air back into inletplenum.... *shudders*

I got a tip GGR might have a suitable enginebreather and oilseparator kit combined. Anyone have any experience with this kit? Knowing GGR (regular FastFord/Performance Ford reader) it will be a serious piece of kit and could well be up to the job solving my problems. Will be costly though, I guess.