Who made this offer?? Are they an established and reputable outfit??
I've heard it mentioned before that regrinding cams can be quite risky. You invariably end up with steeper lobe ramps that will put more strain on the valvetrain.
When they said "if it is the same as the earlier ones we can chip it", did they mean P10 pre- '93.5 - as far as I'm aware nobody has cracked the code for the ECUs after that date. For example, Peter Van Brugel only offers a chip for the P10 and not the P11. Prestige only offers the Dastek Unichip for the P11 which is a programmable piggy back computer, not a chip. i.e. Prestige knows that the computers are different on the later cars.
For $817 + GST and about 4 hours labour Peter Van Brugel's outfit can set you up with a programmable piggy back computer. By the time it was installed (4hours labour) the price wouldn't be far off and you'd have a much more flexible, tested and safe system.
Please post the info when you get it.