if the Tyre Width is 265 and the Ratio is 75 this means the side wall is 198.75
Double it and add this to the rim Diameter of 406.4 = 605.15
Now do the same maths with a standard wheel (can't remember what was on a Classic) and this will tell you overall size difference....
If it is appreciable different than the standard fitment you would need a lift - also don't forget the rolling diameter will be different so your overall gearing will be out and so will your speedo...
Also I am not sure if these tyres will fit the standard 16" Classic Rims.....