GREAT finds Pete...glad you finally found your Convertible, and what a model to find!
I really like those Singer/Kenmore/Sunbeam/Shetland-Lewyt/etc. twin-fan uprights...there's a vintage Singer on eBay right now that I'm eyeing. I've seen a few of the later "Singer System" machines (with that funky "pull-up-and-turn" height-adjustment knob) in thrift stores, but they were too new for me. One of my aunts also had a black Singer Commercial twin-fan after her Eureka Bravo died...I went with her to get it (refurbished vacuum) and played with that thing for HOURS. Even though I was only about 9 I do remember that it pulled the carpet up! Unlike the home Singers it was quite durable, and actually had a chrome handle and rubber grip. Had a high-pitched whine to it but wasn't the noisiest machine, IMHO. Would love to know what happened to that one...
Also, I noticed on your Singer that while there is a headlight lens, the lens that juts out from the housing is missing...notice the groove where it's supposed to fit. Not a crucial piece (I personally don't like them) but thought you might like to know. The earlier, more vintage machines such as the Kenmores didn't have them.
--Austin