I can help you guys with this... 98mm for the black text 100mm including the clear border (1mm each end). In terms of positioning, from the centre of the rear axle to the right hand edge of the clear border 70mm 😉
Found this on Facebook this morning and looks a bargain for some early UK mtb history. I particularly like the project 2 style forks with chrome dropouts and brazing.
I follow just their facebook page. I went to the one this morning at West Buckland as wasn't far from me. Over 95% of the stuff there was road stuff and I came away with nothing.
No worries, I'll keep my eyes peeled for one and let you know (or if mine magically turns up in my loft)! The logo on the original was stitchedon from what I recall (again reflecting the quality) so if you do get one made up worth looking at companies that offer embroidered logos too 😉