1963-66 top question

It is an adjustment thing, the top needs to be adjusted so that it fits well on the windshield & well when stowed. The Manual top MAY go down further because there is no hydraulics beside or below it. The power top is just the opposite, but both tops use a boot to cover them. Unfortunately, you will probably have to get one custom made. I haven't seen anyone reproducing them & VERY few for sale. As far as having to stretch the top, this is common so the top looks good when up & doesn't have a lot of sag in it.