I'll build your system for $1G (maybe per day).
Remove two numbers, like the $!G total labour, and $5G total cost and you could have your drive train and a better boat in the process.
But clearly that was your point. An old POS gas engine is always going to be cheaper, hence the reason I use them.
Well sure, if we remove the total cost, then OF COURSE I could have a better boat, because money would be no object... but it is. I do not have an unlimited budget. Most sailors i know don't have an unlimited budget. Even Larry starts to hesitate writing cheques after the first 10 mill.
Where are you getting "POS gas engine" from? let's compare apples to apples- I wouldn't put a gas engine in, or take the hack approach of simply strapping a 9.9 hp longshaft outboard on the transom- THAT would be significantly cheaper and easier, but unsuitable.