Is this the end of my V20?

[djfam]

Newly registered to this site, although I have been viewing it for years. Unfortunately, my first post is not a good one....

1983 V20 w/ 1983 Mercruiser 470 - best boat I've ever owned.

When de-winterizing my boat this week, i was running it on the muffs when it died and a spurt of water/oil mix came out of the vent hose at the top of the crankcase (next to the flame arrestor) - maybe a quart of water. I knew right away that this should never happen. The boat had been running for about 10 minutes. (It was a little rough but i figured that was just because it sat all winter). I'm trying to determine what the problem might be and i was wondering if any other V20 owners had experience with this. I'm thinking possible head gasket but also a possible crack in the block or exhaust manifold issue. Either way, I know it is bad. Anyone have any ideas?

Thanks, in advance, for your comments.