the easy way: get an MBK 1680 change the dial with gen/aftermarked 5513/full size Tudor and topic.
if you want to stay with your 1680 its much more complicated -
(the stock datefont is shitty and the dials are not that good).
what you need to do anyway are the CGs, lugholes and insert.
its a long way - and if you cant do the mods yourself - some modders will
take a lot $$ from your pockets...
cheers,
Frank