Any 1911 grips will work on a GSG,make sure you buy them with a cut out for the ambi safety on the right grip.There are always grips for sale on EE,that said ,theres nothing particularly wrong with the grips already on the GSG
Dlask make a really nice set of sights for the GSG,fibreoptic front and a adjustable rear.They were very easy to fit and give a great sight picture.