That's a bad idea for a street car. Especially a 306. The stage 3 is overkill for sure on a street car. Its a 236/242 duration on a 110 lsa. It drives like ****. The computer can't deal with that tight of a lsa. I had one in my 94 cobra before I swapped it for the stage 2. Even with a custom tune my car didn't drive that good. It made great power,but its not the way to go on a small ci fuel injected street car. It had no low-end power and i had advanced it 4 degrees. Not all aftermarket pistons come with 2 sets of valve reliefs either.
I don't think you can get the stage 2 to work with a aftermarket inline valve head on a stock piston without fly cutting.
BTW the stage 2 sounded great in my car. It had a noticable idle and great power. I had a custom tune with zero driveability issues. What little bit of hp I gave up was a good exchange for the driveability I got in return.