The twin carb 55, 60, and 65 were indeed a different animal. No parts other than carbs and some ignition parts were swappable with other Chrysler engines. By 1981 your engine should have the better (in some respects) one piece lower unit. This lower unit was better designed than the older two piece lower BUT the gears were a bit weaker. If the engine is under-propped and hole shots are performed there is a distinct possibility of stripping off the gear teeth. The 10 inch propellers were specific to these engines. They are no longer sold on any site but can be found on ebay. SOME Mercury 40-50 hp props MAY also fit but you need to be careful
The engine was Chrysler designed as opposed to the West Bend designed rest of the Chrysler engines. It was a "Packed block" engine with a 3.375 bore and 2.80 stroke. As opposed to other Chrysler engines with a crank locating ball bearing on the top, this engine had the crank carried by a needle bearing at the top and a locating ball bearing at the bottom of the crank. Connecting rods were much more massive and about 1/4 inch longer with a larger diameter wrist pin. Crank shaft was much heavier that the older 55 cranks and counterweights were a lot larger.
It was by far the best Chrysler engine made. For a two cylinder engine it had PLENTY of torque and useable horsepower. If propped correctly-- I think 10 X 13 might be right but you may be able to find something like a 10 1/2-11 diameter by 12-- it should push your V153 to high 20s and possibly even touch 30-32 MPH with just the driver.
If you want to see this engine in action, go to youtube and search Frank Acampora videos. Look for a video entitled something like Mini Cub Chrysler 60. This is the 1984 60 HP version of your engine. It was my favorite until I sold it. There is also a video in there of my 1971 V153 powered with a 120.
Your V153 is rated for a 90. If you find that you are doing a lot of water sports or constantly carrying 4 people, and if the 55 just doesn't have enough poop, find a used 85 or 90. If you use a Chrysler or early Force engine, all controls will work and you need possibly to only change two wires on the ignition switch.