Update: With many thanks to @deadakaalive, I was able to get SD widescreen versions of the season 2 episodes.
I spent a lot of time blending the different sources and color matching them to ensure the best possible end result, and I’m quite pleased with the outcome.
After doing that, I went ahead and did my best to upscale the results to 1080p. I did the entire season, only checking the results on my computer screen, and it looked pretty good. After viewing the episodes on my TV screen, however, I felt I had overdone the grain, so I’m doing another pass now. I expect to be finished later this week.
If anyone is interested in a link, please send me a PM.