Yes, I'm sure that was a III. The one big difference during the evolution of the III, was the replacement of the bail back for loading film holders (as shown in Dead Link Removed), with a spring back. I remember talking about this with Paula at Linhof & Studio in the UK.
I agree. I sometimes look at Richard Ritters site, and wonder whether it would be worth seeing if he could convert it. Or find a poor, dead III on the auction site, and use the back off that!