[Graham]

We often see a Moggy 1000 in our Small Saloons races, an Anglia now and again and a George Turner Austin A35 is seen a few times through the year.

I was kinda thinking of a Mini Event of cars with maximum rear axles width of 50mm.

That'll definitely rule out sidewinders  

50mm sounds good to me 

I measured my Scalex Mini with wider wheel arches to Ade's , so I think that is quite reasonable.