When it comes to hardening the rolls, I would actually reccomend Hycase (4317) as it case hardens as well as en36a or 8620 but is much easier to get good surface finishes on and can get a very deep case (easily up to .3mm). It's very slightly more expensive than 8620 but cheaper than en36a.

I know Ian Stansfield Smith carry it, also I can reccomend Hills heat treatment here who do vaccum chamber case hardening in Melbourne