Taking bets(no money involved) How long will this engine last?

The only thing I would do that you didn’t mention is when you start it up add some Rislone and run it according to the instructions and then drain and change the oil. I did that on my 340 and got a ton of gunk out and when I finally did break the motor down it was clean as a whistle inside. None of the crap seem to go through the bearings cause that stuff breaks it down pretty good

it will run until you decide to modify it further