Well that was interesting... I fitted a marginally shorter spring and mounted the carriage spigot thing round the other way - oh yeah, mine is one of the odd ones where the spigot mount for the main stand is detachable, they didn't make many like this apparently!
The stand was held so far up it not just sat against but fouled the exhaust and the angle on the spigot meant the stand didn't sit in the cut-outs on the exhaust anymore - so I was wrong, taking the exhausts (which are solid mount) into account.
So, I popped the spigot thingy off again, turned it around and welded the bolts in position I'd previous had. As the stop on the spigot was holding it too low when 'up', I just ground that back and everything now fits lovely - shame she's still very heavy to get onto the stand!
I'll put a proper post together at some point with pictures etc., it'll go on here and or my blog thing...
Fair to say I can see this spigot mount, along with the previous pogo stand, were later replaced!