I know I saw an article the other day on chopping a suburban, but dang if I can find it. Here's another one that may be of help:
'50 Suburban Chop & Section I would have taken the opportunity to lengthen the front doors about 6-8 inches with this chop. Proportionately it would look great.
If you are just talking about channeling the floor to make it lower, I do see some issues, a 54/55 frame might be a better option because of the absence of the rear radius, this would allow an additional 5 inches (approximate) of clearance.
