Thanks for your replies guys. I cleaned the steering box a little bit and took some more pictures to add to the discussion.
Phil, this is indeed a rather simple steering box without the possibility of adjusting the angle. I compared the steering box and bracket with the bracket on my replacement chassis and all seems identical.....no new holes drilled or any kind of shims or whatever. At the dash end all seems to be stock(?).
I had another look and I think i can repair the arch bar without it hitting the filler for the steering box. Maybe the cut was done because it made it quicker to fit the steering box??? Normally the nose panels sit over this end of the arch bar, so access to the filler is only after disassembly of part of the nose or by reaching under the front lip of the fender.
I can't seem to find any modifications to the footwell panelwork, except for the extra space for the steering shaft and pedals...
Alex