Re: Which Mercruiser to choose??
Your best bet is to look for a scrap boat with a cracked frozen 302 in it. Swap your good motor in and use the whole setup.
You'll know the block obviously if you go junk-boat shopping.
Probably a Ford site somewhere on the www that has all the fsb block vintages and differences.
Year for year, Ford Trucks and Ford powered boats got basically the same 302's or 351's or 460's
If your only commitment to Ford power is a couple blocks you happen to have, you might not want to rule out Chevrolet.
Marine parts for a chev 350 are sometimes half Ford parts...e.g. exhaust manifolds. And chev parts, new or used are much more plentiful for marine than the ford ones.
want to run with normal radiator and fan if possible (well...anything's possible)
except that... been discussed on these forums a dozen times. No one has ever successfully done anything like that. And no, you won't be the first.
It makes no sense - the free unlimited cooling water of the lake vs a radiator mounted on a huge tower 5 feet above the windshield trying to get enough air to cool an engine running at full load.
It would take many times the area of radiator a car has.