We have similar challenges. I hadn't played hockey since the 2nd grade then started goaltending at 50. Played 6 years and my hip objected to butterflying. Took 6 years off and I've just resumed except now I'm trying to play and make stops without butterflying as much.
I've spent hours on youtube trying to figure it out watching goalies in the 60's and 70's.
One tip: even though they were playing back then, different goalies used butterfly different percentages of the time. I'm hoping sometimes you can guess where they may fall by watching how far apart their feet are when facing shots.
Here is a video where the goalies have different styles. Although they both make kick saves Jacques Plante is mire stand up and Gilles Villemure is more butterfly
A single goalie may also change during his career. As an example, if you watch the long Tretiak video he is standing up on saves at the start of the video in the 72 series and butterflying more later in the video in the later series.
There are many differences among the styles of goalies who would each be labelled stand up. So seeking consistent lessons from many of them may not pan out for some puck locations and player arrangements.
I've switched my gear from butterfly pads to earlier models so I have to relearn to play with the technical limitations they had. As examples: foam box old leathers, durasoft, foam box pads.
Old time goalies told me they prepared their skates differently for stand up play. Some didn't sharpen theirs at all. Some only rarely. Some used some kind of cross cut sharpening rather than a radius. Some sharpened to one inch. Some sharpened to half inch. All seemed to deliberately take the bite out of their blades after sharpening. Dull skates facilitate lateral movement while on the blades. It also softens the edges that would interfere with turning the toe outward for a kick save and with sending the skate out to the side for a half butterfly with the pad facing the shooter. I've moved from a frequently sharpened 3/8 to a never resharpened 1/2. I'd requested a 1" but the skate sharpener warned that moving from 3/8 to 1" would have been too much of a change for me to adapt to without repeatedly falling.
Here is a 70 video stand up goaltending playlist I've put together over the past year or so. If you click through to youtube you will see the entire playlist.
If you find any good resources, please post links