My not massively accurate calipers say 1.940.
A 350 rod can be machined out to take it (if I get your drift!) I know of one that's been done like this, although not for racing.
I heard of this years ago as the mod that all the 'racers' used but I expect someone out there will know a bit more about the real strength in competition use.
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)