I am going to have to call those numbers very optimistic. Without opening up the motor the highest you can expect on a E36 M3 3.2 is somewhere around 270HP.
This can be achieved by installing an Exhaust, Cold Air intake, Chip, Euro HFM, Higher flow Injectors. The Cam can really help and take the car to close to 290hp (but by no means above 300hp). In addition you may also improve the performance with an new Supersprint exhaust manifold.
Do not allow the RPM limiter to be raised to high or you will be inviting engine failure due to valvetrain failure.
You should definatly change the spark plugs to the new Bosch 4+ Plugs.
You may want to consider adding and oil cooler to this motor as it will help with motor life on hard running.
The next upgrade would be an Individual Butterfly throttle body. This will allow you to improve power through the entire rev range as it will allow you to better optimize your air velocity.
At this point there are two major things left. Major head work. This will allow you to run significantly higher RPM work if done professionally. In addition you would add a lighweight forged crank and pistons and new connecting rods. Increasing the compression ratio.
Tuning the motor at that level will require a programmer and a dyno.
With all those mods I have seen the M3 motor that can produce a good 350HP. But it has a price to match.
You may not want to take it that far but it is nice to know what is possible.