Hi everyone! Recently I acquired my first Rolex, a simple manual wind Precision from 1966. The case size is atypically large for a Precision at 36 mm. As it's not a hugely valuable watch and I intend on keeping it for many decades, I'd like to swap out the crystal for a sapphire and potentially change the case back to an exhibition back, too. Would anyone who owns the same reference be able to confirm the crystal diameter? My online research indicates either 29.3 or 29.5 millimetres but I'm uncertain which one. I'd also like to know if the caseback would be the same size as the 36 mm Explorer? Thank you to anyone who can provide an answer or two!