It is close but that temperature thing is a problem that will catch you out one day.
Here's something to try. The very bottom is too rich causing mid to be weak. Reduce the pilot jet until you need to go richer one clip on the needle. Adjust main to suit.
Timing is 18 so unlikely to be an issue at 55mph. Jetting is the issue.
Power jet carbs are really for engines that rev very high as to avoid using multiple taper needles. This carb will jet in. For most it was probably done a long time ago. For me they have to be like factory smooth or they're no good.