Jack, G'day mate, that's a real clean looking bike you have there, I've always loved the old school yellow.
I have a Pro Design Stator Plate and IMO for up to +4 timing advance you can get by with just modifying the stock plate for free, do a search or take a look at BenBB's Electrical FAQ, Question 54.
The plate is hidden, so there is no purpose in putting the bling where the sun don't shine...
The crank is not a one piece design and is built up of pressed in sections. In high HP applications the crank is trued and welded as a safeguard against "slippage" of the interference fit sections of the crank.
Crank slip would lead to the two crank journals being out of phase with each other.
If the present compression is good and the motor has low hours on it then stick with the stock cast pistons, nothing wrong with the original Yamaha pistons and they can be used with 20~21cc domes. Once it's time to rebuild your top end, you can go with a set of Wiseco Pro Lites.