I have a 49 Ford. I can access the fuel gauge sending unit from inside the trunk. I pulled it out and the brass float had sprung a leak and sank, thus the "empty" gauge reading. I Soldered the hole and then put it in hot water (if it bubbles you got a hole) and found another hole and soldered...
My 63 Cadillac I used to own pulled the crankcase gases right up to the Carburetor using a PCV valve and used a ventilated oil filler cap. I never had any problem with it except you had to keep the PCV valve clean and it was mounted horizontally. I going to do the same with my flathead. only...