BMAUTOSPORT seems very popular with members on here.
Offsets should be somewhere in the region of 35 to 45 for the size of wheels you stated but if you post what you are going to buy you will get the definative answer
I'll have alook at the J sizes on mine tonight mate so you can see how mine fit on my zed - not sure how I could let you know a suitable offset based on what I have though .... happy to measure stuff up if someone can advise