I built an ST-1 a couple of years ago. I want to upgrade it so that it can be used by my son who is learning guitar.

I'm looking for ideas for upgrades to take it up a level.

Here are my ideas:
- loaded pickguard to improve pickups. There's the Pitbull options for about $35, but will any others fit? Or is it better to buy some new pickups and rewire?
- new tuning pegs to help it to stay in tune (it's not bad actually).

Optional
- new bridge. Or might just block the stock bridge to stabilise tuning.
- new nut

Any thoughts or tips?