Regarding 1173, I obtained it from another member of this forum in late 2021 (jbergeson). It is golden yellow and has upright growth. Photos of it can be seen on this post:
It sets hips readily, although I have yet to experiment with it given the circumstances. I would love to try and combine it with The Magician (which is phototropic) or perhaps rosa xanthina, in pursuit of healthy yellows.
Regarding rootstock, I am clueless as to how those even work (I’ve only ever grown own root, and have successfully grown only one cutting). Since I live in a suburb, there aren’t any feral multiflora in my immediate vicinity (although there are many in my part of the country). Basically I’m saying that I can’t do anything with rootstock since I don’t know the slightest about grafting (or much of rose care in general, as I’m only 21 at this point).