Polaroid still makes Type-54 and Type-55 which are 4x5 versions.

That's what I use, but of course it can't be used on your Hasselblad. I'm sure a 4x5 graflok back can be custom mounted to a Hasselblad someway, but I don't know anyone in Greece that can do that type of construction.

I, too, regret Polaroid's decision to drop 664 because I used is in a Polaroid back on my Holga.