Well. . . . . yikes. .
. Unless this generator has the same engine, then it is unlikely that it will accept a bolt on heat exchanger and exhaust manifold from a different unit.
I believe you will most likely want to marinize the generator with components that fit it. You might check around for wet exhaust manifolds, heat exchanger and appropriate pump to determine if it's worth your time and money.
Otherwise might be a nice addition to your house??