The very next day, we did turn it over with the spark plugs out and blew all the water out of the holes (it was the first thing we did).

Then we pulled the engine out of the boat and changed the oil...after that we sprayed WD40 and put the plugs back, tried starting it (out of the boat) and it wouldn't start, was slow to turn. Tried manually turning after filling spark plug holes with WD40 and letting it soak down, turned a bit stiff slightly. Then used "Marvelous Magic Miracle" oil additive stuff in the same holes, let it sit for a bit then tried turning again manually....it just kept getting harder to turn until finally it wouldn't hand turn at all. I filled the spark plug holes with WD40, put the plugs in loose, and let it sit in my garage from September-May (this past week)

There is a light dusting of a hint of rust on the intake holes (the big ones on the head) but no major "rust spots" that I can see. (I thoroughly cleaned the intake manifold already) From this point, I want to put it back together, it hand cranks freely now, more or less. I am figuring on selling the boat this summer anyway. I'm in a small town with no serious local mechanic shops nearby. (we have a few tire places)

What, step by step do I need to do (from here) to make sure the spacing is correct?

And what should the rocker spacing be set to once it's pumped full of oil and in position?

Since I'm not using any new parts (like the rockers and springs), shouldn't I just tighten the bolts till it's firm?