I mean, failing all other options - since you’re going to be sitting upright anyway you can buy your choice of existing 3 speed and simply add a longer seatpost and taller stem. My ‘83 Schwinn Collegiate has a 22” frame and at 5’12” I needed a little more seatpost than the stock one provided so I did just that, replaced the seatpost and stem and now can achieve a sit up and beg position a la Dutch bike. It took 3 days for the stem and seatpost to arrive from eBay, total cost $25, paid $40 for the bike and $40 for new tires, overall investment about $100. It does have the crappy Shimano hub but I don’t ride it that much. This is the best photo I have unfortunately.
