What are the ussual 470 issues ?? And if its seized what engine should i pick ???
to expand on above
the 470 has an iron head and aluminum block. the block has an open deck (floating bores) because it was cheaper for mercruiser to build and they didnt spring for the aluminum head. so as much as a 10 degree overheat and the block moves enough to blow the head gasket. the fix for this is a bore spider welded in the block to stabilize the deck and an aftermarket edelbrock aluminum head
the inherent issues with the ford head, valve train and non-adjustable rockers requiring different push rods for any head work, GM style block/cam, GM style timing, GM flywheel and custom mercruiser crank......
the heat exchangers that were originally paired with the engine were too small. this lead to large amounts of overheated engines and blown head gaskets. eventually mercruiser installed a larger heat exchanger
the water pump is driven off the cam snout. the cam snouts were never hardened as that would have cost money. so the seals wear thru the cam snout material. the fix is a speedi sleeve.
the stock charging system was pulled over from the outboard lines to be cheap. the charge output was modest as it was only intended to charge the battery and run lights. not enough output to run radios and other electronics. however the regulator is the week link. since that is no longer being made in high volume, that little water-cooled beauty is about $500. hence the aftermarket external alternator conversion
most of the parts for the 470 are NLA
as to replace it. I would find a complete and running 4.3, preferably with an alpha 1 gen 2 and swap the motors pulley to prop