Hey Karl ………..
"it's Me" !
I see your picture of your "broken exhaust manifold" . ………………..
so, Look up " Marine - Tex " ……… a two part mix , "thick putty kind of paste" , and I've used it for years : to patch 'gas tanks' , Big electric motors , AirPlane Props ( wood two blade props - - for "air boats" ) . So as thick as the broken spot , I think it would work (for a 'cruiser motor' ) , if "the broken area IS CLEANED properly " . . . . . . and would be worth a try.
We used this stuff back in my body shop days - - - mostly too repair those front "Fiber-glass Header Panels" on the Olds 88 & 98 , some boats , ect.
Last time I looked it was $$$$ , so look at it , and if nothing else - - - it would work until you could find a replacement.
I buy the Gray Product in a Qt. size can …………………………..
and, on the older cans - - - the label even stated : can repair
"cracked engine blocks" . Keep clean & sealed - - it will last for 5 - 7 years.
http://marinetex.com/products/marine...x-epoxy-putty/
I'm just saying . . . . . jim - - - - (it's been my "go - to " product for years ) .