My 1939 216 has 30 psi when starting cold. After it warms up it idles 5-10 psi and 15+ when driving. That's about normal for a 216. My engine runs great.
Reasons for anti-freeze in the oil
Cracked block
Cracked head
Cross over oil line leaking
Bad/wrong head gasket
Head not torqued down properly
Block/head surfaces not cleaned/machined properly
I had a Ford 1963 262 engine that had been rebuilt. While adjusting the valves with the engine running the oil turned milky. Retorqued the head. I drained the oil, replaced the oil filter and oil. Problem solved.
Rick