I've installed quite a few. It's not rocket science.
The tops for the new cars 88&up come with lines on them to line up to get a good start on the bows & driptray
The old cars I try to align them in the quarter glass area 1st then go out from there.

If I were you I would research around your area & find that old guy that has the best rep for doing it & pay him.

I've seen a lot of shops that do show quality work but struggle with a old convertible top.