I am a fan of that engine, maybe the only one. I've got the same engine in my V174. The "470" engine is about 6 inches longer than the GM 4 cylinder 2.5 & 3.0 Liter engines, and with the alternator conversion kit sporting the add-on pulley then add another 6 inches on top of that for clearance. So, if your engine bay can fit a GM in-line 6 engine then you may be able to fit the "470" engine. You''ll probably have to mod the boat by moving the front engine mounting plank further forward. Compressions readings should be 140-150 psi/cylinder on a good engine.
The one you're looking as has got the original style exhaust manifold and elbow which are no longer available so if you ever had to replace them you'll have to upgrade to the newer version. You may have clearance issues getting the old-style manifold with the coolant reservoir up front to fit inside your engine cover. The newer version manifold has the coolant reservoir in the back as part of the elbow, something to think about.
The engine has closed cooling which circulates glycol like your car engine through a heat exchange system. The early 470's had a 3 inch diameter heat exchange cylinder but many people upgrade to the later 4 inch version for more efficient cooling. I would look into changing out the points ignition for a Pertronix ignition. I did that and it idles and runs so much better vs. points. As long as it's been well cared for and maintained and the engine isn't making any unusual sounds like tapping or knocking and the compression is good then they are good work-horse engines. Sometimes they moan a bit when first started because of an oil bypass valve but it's momentary until the engine warms up. Also check for oil or coolant leaks. With the bigger more powerful engine you'll also have to change the drive so the gear ratio is more accommodating. The 3.7 and V6 engines use the 1.84:1 ratio, the donor boat may have what you need already on it. Feel free to ask any more questions, I'm off to work now.
