Thanks for the replies. Seeing as how I live in a subdivision on a 1 acre lot, it's kind of hard to justify 2 G1900s and a BX.
Thanks for catching the missing air intake bolt. I had it loose because I kept taking the hose and air filter off several times and forgot to tighten it back. It's somewhere in my yard now.
This project has been very interesting. I can't imagine trying something like that without folks like North Idaho Wolfman, johnnyFbomb, and D2CAT, etc. willing to be online tutors. That, and the incredible amount of archival material on OTT and other sites.
I mowed with the rebuilt machine yesterday and it performed well. Very hot and humid day and it ran cool all day. I mowed my lawn, the entrance to the subdivision, the community pool area (1 acre or so) - pretty much anywhere I could find that needed grass cut! Got in 2.5 hours or so and was really pleased with the mower.
A couple of lessons learned:
1) The o-ring for the oil pipe that should be installed with the head gasket is an odd size, 6.4mm (id)/11mm (od)/3.5mm (width). Rather than drive 1.5 hours to a full service Kubota dealer, I found one in an o-ring assortment from an auto parts store. I first--unknowingly--used a regular, thin, o-ring and oil leaked from the head.
2) If I take the engine out again, I will remove the steering wheel frame and remove the engine and radiator together. Trying to "work the engine" under and around the radiator is a pain. 15 minutes and I could have had free access by removing the steering wheel and frame.
3) Taking pictures and notes will help when time for reassembly! I was surprised at how many times I referred to pictures and notes, even when I thought I pretty well knew what was what.
Thanks again, OTT friends.