I run Comp 986 springs and had to have the heads machined.
BTW- I make 350rwhp with the CC306, letting of at 5900rpm due to the stock timing chain.

 

I've been thinkin about gettin a CC306 for my car... what stall converter speed should be used? (i heard if it's too low stall speed like factory the car will die with a cam that large... true or not?) and what would you all recommend springwise to use without getting the heads machined?

 

as stated above the ex612 springs , no machine work needed, with a stall of around 3000 rpm