1988 Four Winns for sale for $750, but has milky oil dipstick. Should I go for it? Thoughts?

Right down the street from me, there's a 1988 Four Winns for sale for $750 OBO. ITS VERY CLEAN. The man says it starts and runs and the IO tilt prop works. He made a video to back all of that information up. However, he forewarned me of a milky oil dipstick, he does not know much about engines. I know it has to be either a blown or cracked head gasket or a cracked block. But I read a lot of articles that say it's more than likely the head gasket.

But, if it is a block, is it true that I can repair it myself with JB Weld?

The engine is a Ford 351.

If it is the block you MAY be able to fix it with JB - won't guarantee a permanent repair though.
More likely the head gasket (unless it uses raw water for cooling & has been run in salt water then all bets are off.

Your never going to fix the block with a gimmick, it is most likely the head gasket, an expensive engine repair

I agree, if its OMC do NOT get it. Mercruiser is the way to go. And JB weld will not "fix" it. It will bandaid it temp. And do not take a video for proof it works. Make him run it with you there. Again. OMC == DO NOT BUY IT

Does it get cold were you live? Question the owner about how it was winterize. If he messed up figure an engine and 2 manifolds, I have fixed external cracks with gray marine tex buy drilling the ends of the crack and grooving out the crack, clean it and add the epoxy.
It could be a head gasket, check compression.
I will come out to around $1000 to $4000.
If it is an OMC white drive do not buy it, parts and service centers that will work on it are getting to be few. They are also called stringer mount drives, beware.