So far nobody has discussed the different gear ratios available for the "39 transmission."
Suggest anyone who is interested go over to the Ford Barn Early V8 forum and search "transmission ratios." There's quite a bit there, and any discussion about the benefits of using an early V8 transmission should include gear ratios as well as the synchros.
(For those thinking about the swap, be aware that some later cases have reinforcement ribs on the bottom ... "supposed to be superior", but aren't ... the rib interferes with the wishbone adapter and grinding may be required.)