As far as the pickguard in concerned, go to WD MUsic Products.
They make many different options that fit the jagstang like a glove!
Follow this link:
http://www.wdmusic.com/pickguard_jgs_1200.html
As far as pickups are concerned, I have a Duncan SSL-1 in the neck, and Duncan TB-4 Trembucker in the bridge.
Pickups will only get you halfway there. You must change out the crappy Japanese pots and wiring they use.
As soon as you change out pickups, and do a complete re-wire with quality parts like CTS & Switchcraft, THEN YOU WILL TRULY NOTICE THE DIFFERENCE!
Follow this link to listen to audio samples of Seymour Duncan pickups:
http://www.seymourduncan.com/support/audio-samples/
HOPE THIS HELPS!
CHEERS!