"I'm considering removing the PCV valve and going full open tube from valve cover gasket to intake"
Assuming the pcv valve is functional, open tube vs open valve shouldn't really matter....There is no good way to reduce crankcase pressure from blowby (I just spent the last month working on it in the willys....it has a road draft tube instead of a pcv system, but similar idea to your open tube, except it vents the excess pressure and dumps the oil on the road below as you drive instead of feeding it back into the intake for combustion (was a different time with different concern over emissions etc). There are oil traps/catch cans that can be installed in the pcv hose to reduce the amount of oil going into the intake if its becoming a problem and affecting engine performance or fouling plugs etc....also give an idea of how bad the blow by is by how much oil collects.....I had issues with blowby in my 4.2 cj7 - except the pcv feed into the oil filter housing and not into the intake or below the throttle body at the base of carb - so it would ruin paper element air filters rather quickly and then get sucked into the carb clogging the carb....Much as you say, its worst when you are at highway speeds (high rpm with no OD or large tire/gearing issues) or in the mts pulling hard. The wagon is doing the same thing right now, and the crank case pressure is pushing oil out of every seal and gasket there is.
Oh - and just my suggestion - a new/rebuilt/reman engine is awesome (its made my cj5 a different, totally reliable vehicle), but one day I'd suggest considering doing some gearing to help move those 35s along and allow for full use of your 5 speed