TL;DR - Get on a Mac, install Transtype trial, and convert the files, even if it gives you errors when adding them. Just do it and you should get some functional TTF or OTF files.
I'm on Windows 10 1803 or whatever the current version is, coming from Windows 7. I work at an agency and we've got tens of thousands of font files and almost all of them are PostScript Type 1, which was aggravating for me at first, but eventually I managed to set up Windows 7 to render and deal with them, I think by using GhostScript. I can't make heads or tails of what to do with it now so if anyone can look at it and figure out if that can make Windows handle Type 1 fonts, awesome, please share. In the mean time, I've downloaded Transtype (trial) on one of my coworker's Macs and it did the thing. It made TTF/OTF files from the old Type 1 files, even though the Type 1 gave Transtype errors on the Mac. I'm going to be possibly talking the president into purchasing a license so we can keep using all of our fonts. Hope this helps!