Thanks guys, very nice for you to comment on the pair!
One more full day until I can try to see if the KBS sealer works. It for sure seem solid inside but "looks" doesn't tell you much. If it actually runs as well as it did when I first steamed it up, I'd be very happy. As of now, when I close off the vent valve and I give the wheel a good spin, it makes a nice vacuum - which you hear when you open the whistle (you hear a "swish" of air). Considering this is a oscillating piston, that's certainly a good sign.
If sealing/running is successful, I am going to paint the engine, as I need to stop the outside from rusting. I decided on Rust-Oleum Silver High Heat for the tank & their Black for the lower base. Then I have some model paint for the little bits that are gold & red. I'm likely going to leave the lamp base alone as I want that to be a possible donor.