[Graham]

As I said I will go with whatever you decide as the host.
It does appear maybe the Carrera Porsche is a little wide (research suggests 65.6 ish mm), but the Ferrari is pretty much correct, much to my surprise 
Try getting one of those in your 60's UK garage  

The rules are much the same as last years "InterSeries" except for todays limit to 10mm tyre width ( last year it was max 14mm).
So your Ferrari should do well again, I am not sure that Courtney will be entering with his superfast Porsche 910/20 as he has been very busy this year, so your chances are probably significantly improved