Fill to 7 and top at 6. On my 177A O 360 Cardinal, it was always all over the belly. I installed a Walker air oil separator & it helped immensely but not a total cure all. With the chrome top on this engine, I average 6 to 7 hrs a qt and my comp was all in the high 70's.
My RV4 with an O 360 A1A fill to 7 and top at 6. And I'm getting 25 hrs to a qt. This has an air oil separator as well and only minimal oil on the belly. Comp in the Low to mid 70's.
There is a huge variance on each engine. Anything with a chrome top (cylinders) seems to always use or lose more oil.