That looks like a lot of work to get that far!
Good luck in getting it all done soon! And you are already 72? Wow, I hope that I am that willing to do work on the RV in another 20 years when I turn 70.
Hopefully you can chirp the tires with the new engine! I would recommend 91 octane fuel, as lower octane will chance pinging, and that will cause the computer to run it rich, as well as back off the timing, both will lower the MPG.
Hopefully you will not be running out of fuel too. The pump is only good for so many HP. . .
Fred.