I don't know for sure but I really don't think there is any difference at all between them. they take a 455 and install all the necessary marine hardware. Whomever does the installation might change the cam and intake/carb but that's probably about it. If you want to build a stout 455 then I would highly suggest forged Wiseco pistons and Eagle forged H beam rods just for starters. Bernard Mondello alum. heads (not to be confused with Mondello in Paso robles, Ca.) Harland Sharp rockers. and ARP main and head bolts. Other members will be by to include thier shopping list. A good balance job will be a must do for sustained high rpm in jet boat ........ or car.

 

A lot of boat engines had K heads, which are nothing special..
You might want to do your research, boat 455’s are run at constant rpm, and the oiling system will need attention, to assure lubrication at sustained speed. Bill Travato’s book is where I would start.

 

Look for water jacket corrosion in the block and heads. It may be heavy and can interfere with good cooling.

The ideal way of removing that corrosion is through an electro-chemical process. The last commercial concern that I knew of doing this was in Indiana 10 years ago. Blocks would come back looking like they had just left the casting line.

I don't know if they are still in business. The problem is disposal of toxics, which cast iron should not generate.

If you want to read about the process, here's an article: http://oldengine.org/members/orrin/rustdemo.htm

If you're good at following directions exactly, you may decide to try it. Otherwise, skip it and buy aluminum heads.

There's a lot less heat rejection to the block; if you can still see between cylinders, you should be OK.

 

Had Nick at AMR make me a set with bungs. Makes my Hooker super comps look like child’s play. Dual bungs.

 

Beautiful! I just got my ARH's as well!