[sack54]

To bad about the paint job, It can be fixed pretty easy. Now for the vent window
You have nothing to loose now ,how about cutting rivets out of the mounting tabs and put them where you need. then drill new holes and remount the tabs
in the right location, Plus when the tabs are removed you can test fit the window without the mount tabs, to check the fit . Rivets are easy to find or you can spot weld the mounting plates where you need them. Also masking tape first then put a couple of layers of duct tape over masking tape a lot better ,holds up a lot better when trying to install windows.
Good Luck