DOGS BOLX was one the first suspension corrected frames but was only built for a 63mm fork - original RC-35s, Manitou 1 & 2, Mag 21s etc. It just looks too high at the front.
To some of us, it looks too high at the back as well!
I'm surprised by what you say about the geometry though, I thought Roberts offered full custom, so the head angle/fork length would be whatever the original owner specified. But I get the impression that with Chas Roberts, custom can sometimes be a 'you'll have what you're given' kind of custom, so is that why you reckon they were all 71 deg/63mm?