rogervize

Hi all. Newbie here. I am restoring my 1974 TY250 (I bought it new) I would like to swap out the standard 428H chain and sprockets for a 520 size. Is this a common modification? How do I go about this? If I don't do this mod is there a source for standard sprockets? I am thinking of close to original gearing of 14/52. Thanks for any advice. I am located in Melbourne Australia.