Welcome to CHR. The chop part of a glass A sedan delivery wouldn't be that difficult, depending on how much experience you have working with fiberglass... If you don't have a lot of experience with glass I wouldn't recomend chopping as a first project. Channeling it would be a bit more difficult.

Maybe contact one of the manufacturers of the 'glass bodies and ask them what the charge would be for them to do it? Especially the channeling, it would be easier to relocate the floor during the body assembly rather then have to cut it out of a new car and move it...