Over several hours, yesterday and today, I removed the cab floor plates for better access to what lies beneath. Thought it would take ages with a grinder, to remove all the weld nuts. I was wrong. It took ages with a cold chisel instead. I couldn't bring myself to use a grinder in case I slipped and marred something irrepairably.
All in all, the cab frame is very good. Worst corrosion is on mates side wheel arch inner, where the mud would have sit & festered! It is pitted but does not go right through. I know this because I ran over it (and the floor plates) with a descaler & then the twisted wire cup.
This is the typical state of floor plates, but mates side front piece is worse than other side. I had initially reached a decision to replace all the floor plates due to the degree of pitting (no rust through, just ugly appearance). Now i'm having second thoughts. It still looks sort of ugly, but it IS original, and it DOES add a vintage patina (spelling ???). I'll sleep on it. Will go ahead and take patterns from all three pieces for puropses of manufacturing repros in future.
Can someone please tell me if the irregular shaped hole, second from the right, is original or a bodge job in later life. It does have bolt holes tapped in the floor plate but it doesn't look as 'neat' as the work on the other holes. It doesn't have any support plates or other things underneath it either.