You have received a lot of great suggestions already. I would, as already mentioned, check the PCV system closely. Starting with the PCV valve, the PCV hose from the valve to the rear of the carburetor and the hose from the oil cap on the rear of the right side valve cover, up to the crankcase emissions filter inside the air cleaner housing. I have seen those hoses collapse and occasionally have done so internally with no visible signs from the outside. All engines are going to exhibit some blow-by to some extent. If the PCV system isn't functioning properly, you will experience front and rear crank seal leakage. Ask me how I know!
And my true story goes like this. Glad to see someone else besides me has experienced "Dipstick Syndrome"! I had always heard size matters, so when I was offered a 4bl carburetor from a 428 Police Interceptor to install on my 71 "M," I jumped right on it. My original setup had a hose from the PCV valve in the L/F valve cover to a stub on the rear of the carb. The 428 P/I carburetors didn't have that stub fitting, so I just removed the hose and valve. That's just more junk under the hood, and that's why they made regular oil filler caps, right? And that would also make me a member of the throw-away club like my buddies that were throwing away all those Rochester carburetors, rev limiters, and ram air housings.
It didn't take but two days, and I had oil everywhere. Oil was seeping from the front and rear crank seals and the dipstick was actually pushing out of the tube. (Usually after racing or beating it to death like I usually did) I thought the car was possessed. When one of the shop techs looked at my car and saw what I had done (I can't print everything he said), I was made to understand the words "Crankcase ventilation" and Dumb A$$"! That was many years ago, but I still should have known better. It's something I have seen many others do, but you know how that goes when it's something of yours!
The photo below illustrates the baffles (circled in red) Cleveland Crush had mentioned in his post.