So I previously used a manual caulking gun (those hand-pumping ones you see at Bunnings) and they were horrible to use - hard to get a consistent bead and a mad workout on the forearm muscles. So I bought a pneumatic caulking gun. Sealing 3-piece wheels is something I'm not willing to cheap out on, and after seeing my wheel specialist use one for one of his jobs I decided it was something that I needed too.
And what a massive difference it made. It took all of 20 seconds to completely bead the wheel. A smear over the bead using my thumb finished it off.
And that's done. Took two days to cure (still felt soft after leaving it overnight). Here are some pics of the wheels in its completed form:
Black chrome bolts weren't really chrome at all, more of a satin-look, but I prefer that.
And finally some pics with 195/45R15 tyres mounted up and on Tony's EK.
Final specs ended up being 15x8 ET12.3 with a 2" stepped lip.