It is strange. I do know that the harcore 1655 collectors have inflated the market via snatching up as many 1655 examples as they can - and slowly releasing pristine examples into the wild. In essence, these collectors have created their own relative worth in the vintage circuit. I think, thanks in part to these guys, we have witnessed zero case replication attempts. 1655 is rare (we know that already), and wholly unique as far as case size goes.
I HIGHLY doubt that any of these 1655 collectors will ever put up an OEM case for 1:1 replication. It will never happen as they need to guard their investment(s).
Somewhere, there must be exact size information regarding the case size. This is what we should hope will surface. Oh and I guess we need a slowbeat GMT movement, too (I ain't gonna scavenge a 1575 movement).