OD unit operating piston rings?

OK, I spent part of the day cleaning up the internals to the BN2 OD unit, this included some hot tanking and evapo-rust soaking. I managed to get most of the piston rings off in one piece but one of the operating piston rings broke, one of the single ones underneath the double ones. Since I'm more familiar with LH type OD units a la MGB, I wondered if anyone had replaced the metal rings on the early pistons with rubber o rings. Anyone?

I checked them with my caliper and the groove dimensions are spot on for the Parker recommended size for a 1/8" o ring on a 1.373" plug (piston). They're so correct that it seems as though they were designed to run o rings.

This groove size takes an AS586A-216 o ring in whatever desired material.

Anyways, if someone has experience with this, please chime in. I don't see why it wouldn't work, designing mechanical stuff with o ring seals is part of what I do where I'm currently employed.

If no one knows, then I'll be doing the experiment.

Here's a shot of some of the bits, finally managed to get the input shaft nut off and press the bearing off, ready for a new one.

You can get replacement metal rings, and you can also get later model (O-ring style) pistons to put into the earlier units. Personally, I wouldn't swap them in partsies__only wholesies...