'F' types were modified even during the brief production run and, with hand craftsmanship and varied parts suppliers, no two cars are identical. The factory approved/carried out the retro-fitting of later parts.
In a 'bespoke' era, customers could order cars to their individual requirements (at a price) and, apart from bodywork from specialist coachbuilders, items such as extra instruments and colour-schemes were available - including coloured steering-wheels...!
The MG factory's experiments with superchargers led to the development of the 'K' type engine with its cross-flow head and smaller capacity to fit within the 1100cc class for racing, but many owners have followed suit and fitted superchargers themselves.
Down the years, various engine replacements have been tried - from American V8s to Coventry-Climax, but the preferred choice nowadays seems to be the 'N' type MG. Of course such changes often necessitate modifications to brakes and even steering.
'F' types have been modified in many ways and suffered indignities - even fitted with independent suspension and bodies from other makes! Alas, period parts have even been discarded because 'wiseacres' thought all MGs should look the same! Vive la différance...!