On my last engine it used to blow oil out of the dump valve and this was due to heavy crankcase pressure!! I tried a breather system it cured it a little then I dis connected the metering head return (blocked off the Metering head) and ran it to fresh air but still not much joy!!! It never smoked up until the last month or so before my engine died and when I stripped it down I had two big chunks missing off 3+4 pistons !!!!

Try and turn the boost down or strip the engine