They are about 140bhp I think, same engine as in Bluebird Turbo's. They are called CA18ET and are similar engines to the CA18DET found in S13 200SX's but they are single cam rather than double on the S13. No intercooler. You can do a few mods to get more power out of them. The rear axle set-up is no where near as good as the S13 though.

You can buy a S13 for £600 but you'd be hard pushed to buy one for £600 that won't go pop after the 1st drift day you do. If you buy an S13, you'd want to have some money available to fix it. With the S12, they are an ugly duckling so £600 will get you a better car.