500 horsedpower is possable but very expensive.

I been a dyno operator for 20 years and I NEVER see any tune Port 355 with 500 hp.
The Most I have ever seen is with a 400 tpi. It only made out of a stock tpi 300 HP but the Toque was at 500ft
It was a great street engine!
It redlined at 4200 RPM

You never get that power out of a NA 355.
Know I have seen LOTS of TURBOS and superchargers push 355 up to six hundred horse witht the stock tpi.

It can be done but you MUSt have boost

 

I definately agree with that given only 355 cubes. A bigger motor might be able to do it, but even that may not be possible given the airflow restriction.

TPIs are limited to about 5,000 RPM. All horsepower is is a measure of torque referenced with RPM. Without the cubes to build massive torque down low, and without the airflow to support high RPM there's simply no way to get horsepower like that out of a TPI. It's a mathematical imposibility.