Kaiser Bill Brown did a review on the floorboards that are being sold on ebay and he claims they are not a good fit and don't really work. I've heard others make the same claim. Bill has some good information at
http://www.kaiserbill.com/page46.html He had great section on how to repair the floorboards but I see it's under construction now. You may be able to call him or contact him via that page.
Strangely enough, in all my years of working on Henry Js, I have never had a door off one. The shop manual says to drill out the rivet in that center door hinge/stop and install it with a new rivet upon re-assembly - a nut and bolt may work for that.
In my opinion, it would be impossible to restore a Henry J the right way, without Rudy Phillips' parts catalogue.
Rudy can be reached at 1-760-789-3608, mornings are best to call. You can also write him at 2136 Walnut Street Ramona, CA 92065
If you are going for an exact, authentic, restoration I would advise visiting this site:
http://home.comcast.net/~ljfid/Also, Mike Hazel and his dad did an outstanding body-off resto on a 1951 a few years ago. Much is the same on the '53 (although there are some significant differences too so ask questions if you have doubts) and you can see his chronicle of the work at this site -
http://www.henryjcars.com/hjc1p1/hjcp1index.htmlRegarding some differences, you mentioned you needed seats; the 1951/52 seats will bolt right in a '53 but the true '53 front seat is larger, thicker and more comfortable to sit on than the earlier ones. Tex Dean in OK may have some seats, his number is (918) 341-4813 and the last e-mail address I had for him is
TJSPJS@PRODIGY.NETLet us know if you have any more questions.