haven't chopped one but i did unchop one of the poorest chops i've ever seen on a 31. they look almost like you can cut then lower and reweld but there is about 3/8- 1/2 inch difference per 3 inches of chop that you have to account for otherwise you end up with too much metal on one side and short on the other. these guys just started on one side and by the time they got to the other the door post was about 5/8 in off so they just folded the metal over and wasted about 4 sticks of braze rod and lots of mud to try to hide the gross error i'm sure some alcohol was involved also. remember that you also have wood members to contend with, also the vertical body seams and strips.