Hi Allan. welcome to the club. I've only recently joined up too. You'll find this place is great, with lots of active members who are happy to help out, and some pretty interesting projects under way.

A Sunny with a SR20 turbo will definitely surprise a few people. How much work was involved in the Stanza diff swap - does it bolt in?

For front brakes, you have heaps of options. One of the better ones would be the fairly well known Verada disc (blank) and Commodore caliper. A cheaper and easier option is MR30 - R31 struts and vented brakes. With good pads these would probably be up to the job.

But if you want to do this legally, talk to a Dept of Transport approved engineer (who will be doing your mod plate) about what will be required for compliance. Transport keep a list of approved engineers.