I mounted my suction side fitting to the pump on top of the front of passenger side valve cover with the bypass valve beside it with the instructions I receive from GZ motor sports on my unit right next to suction side fitting. I added a long thin full width baffle with 1/4 inch holes in it under both fittings so it can suck oil off of the rocker arms and pushrods.
On your deal I would add a baffle and move the pressure relief valve to the motor as close as i could get it to the vacuum hose
I had similar issues with mine at first until I added the baffle, it was blowing oil out of the breather cap after two runs, not anymore