Heavy Breather!

I think a leakdown test would be on the top of my list.
Make that second.Or maybe third.
1)I would first verify that the crankcase oil-level is not overfull. When the crank gets to beating up on the oil, all that aerated oil has a hard time getting back into the pan in a timely manner.
2)Then, cuz I have the tool, I would do a blow-by test.
Then, if the oil level is correct,(dont trust the stick calibration on an unknown engine), and the blow-by tester indicates and confirms a problem;
3)then I'd go looking for a scored cylinder wall. I use the same LD setup. I just crank the pressure way down,and back the piston part way down the cylinder, stopping in several places, to check for air sneaking around the rings; especially when it gets to where the wrist-pin lives.Oh-Oh......
And of course, before I would do any testing, I would install those pesky baffles as already mentioned, and some large breathers with oil-separation capabilities, you know, the ones with the mesh inside.

On another note. If you are gonna put a smaller cam in that engine, you have to be careful that your Dcr and cranking cylinder pressure do not exceed the octane limits of your locally available gasoline. So a compression test will serve two purposes; 1) to see what we will see, and 2) if there is room for a smaller cam.