Nippon Denso 500hp pumps can be had for $250, direct fit and work a treat
EDIT: Petroject in melb have them but thats retail, if you can find one on the net on something like nengun etc youll get it for around $250
But the bosh pump should pose no problems if its installed correctly, I dont see why youd remove if it its working correctly, also have you taken it back to same to rre-tune it? maybe he could give you some suggestions
Jez