I run 16"x8" rims on my 65. You will need to do some minor clearancing to run 16" rims. I'd kind of hard to explain, but it has to do with the positioning of the upper control arm inside the wheel. A 15" or smaller rim will clear inside the control arm and spindle and a 17" or larger rim will clear outside the control arm lip. but a 16" rim will interfere with stock type control arm. It's not that difficult to take care of that with a grinder, just some light notching will clear the way. Also, most reproduction control arms already have the problem area notched enough to clear the 16" rim's inner lip, so if suspension was rebuilt, you may not have any clearance issues.
It is necessary to do the Shelby front suspension modification or use a "negative wedge" kit to change the camber curve, otherwise you will have problems with tire-fender interference.
I run 225/50/16 all around, but I've seen others run 235/55/16 in back. If your front suspension is lowered a bit, you might have better luck with 215/50/16 size tires, but those are not as easy to find as the 225s.
Good luck!