In digging around in my catalogs, I find my info about Niagaras is older- the 164 must be a more recent designation, as I can find NO.s 1 thru 4 for deep throat beading machines. The number 1 thru 3 were rated at 20 gage, and weigh 100 to 170lbs, depending on size. The number 4 was 26 gage, and weighed 50lbs.
The deep throat models havea bound bar on the bottom which the stop slides on, and a casting on top.
Usually on the beading machines the dies have a round hole, with a keyway slot, and then there is a nut that holds them on, with two holes for a pin spanner to tighten it. This is the way my Pexto works- and from catalog illustrations, it looks like Niagaras worked that way too.
Cant you measure your existing dies?
Roper Whitney, who owns Pexto, still makes dies for theirs- here is a link to the styles-
look under beading- does yours resemble a number 622?
Here is another style of bead roller- while the pexto's may fit your machine, these definitely wont, but they are interesting nonetheless
Williams sells some rolls, and claims his are interchangeable with tennsmith and pexto- since Niagara hasnt made em in so long, it could be he just doesnt include them for that reason- and he also sells blanks, ready to machine to your own profile-
Tennsmith still makes these machines, their rolls might fit
And then there are the chinese imports- Jet, Grizzly, et al bring em in, mostly from TSMC (Taiwan Sheet Metal Corporation) as far as I know- again, they may be interchangeable. Check with Jet for spare rolls.