Checked out their first two albums recently and really enjoyed them. Any other albums by them that are worth me giving a listen?

You can't really go wrong with any of their albums, but "Unreleased 1985 Album", "Master" and "On the Seventh Day God Created... Master" are easily their top three albums, with "Unreleased 1985 Album" being the very best of them. But you could just work your way through their entire discography. Good, solid and incredibly consistent band.

But I would first and foremost recommend the three named albums, and then gone on to check out Paul Speckmann's other projects such as Death Strike, Funeral Bitch and Abomination. These three projects are also incredibly cool. Death Strike is the best thing he has done IMO, followed by Funeral Bitch and "Unreleased 1985 Album".

I checked out the Unreleased 1985 album only to find it was just early recordings of songs from their first two albums. Is there any other albums worth noting by them?

What about Death Strike or The Speckmann Project? They're Paul Speckmann's other bands & they're pretty similar to Master.