I know its possible with modifications. I remember seeing a picture of it somewhere (on here I believe but I couldn't find it).
Anyways, I know the frames are different, but here was my thought.
Switching out all the cross sills to the 54' spec. then just using the 47-53 bedsides, front panel and tailgate. The truck came with a "year correct" bed to replace the 73-87 bed which was on it... being a newb to the classic truck world... I missed this when I purchased the truck. The PO said it was a 54 bed... which it wasn't... it was the earlier version. Everything is in fairly decent shape metal-wise.... so I'd like to use it (as I'm on a very tight budget like most people).
Any tips/help would be appreciated! Thanks fellas!