Fast67Ford,
Do you have access to a welder? Or know of anyone with one? Even a local shop? This is so easy a caveman can do it!
ALL you need to do is get the appropriate size nut and washer for the bolt you will use to fasten the body to the frame.
Take the nut and weld it to a flat washer (make sure its centered to the washer). Then weld a scrap piece of steel (all shown in the below picture) to the flat washer.
Take a measurement of the hole to the centerline of where the bolt will pass thru and transfer that to your newly made "clip nut" and bend a 90 in it. slide the nut thru the hole and align it to the bolt hole. Install a bolt in the nut and tighten to aid it from falling in the frame. Now take some tin snips and cut the access sheet metal and use a hammer to bend the tab down. And viola, Your ready for the body.
If you do not have access to a welder let me know. I'll see what I can do for ya.

[addsig]