I am in the process of an M416 restoration as well... picked it up off ebay for $200.00.....the floor or the tub was toast and some moron cut a real crappy tailgate in it...so it was going to need a new floor and the back rewelded...then I found this www.manleyorv.com
he had some blem tubs on ebay for $350....SCORE. they are the same size as the original tub and I am mounting mine of the frame hopefully today. I decided to stay with the original tire/rim set up with the NDS tires ect... had a hard time finding shocks for it...ended up getting the from WillysJeep parts out of Phoenix AZ. I need to throw some pics up here..... good luck with your project.