question about timing system
 

do they have a chain for the dohc? or like a chain kit

A belt turns one cam via the crank, then a chain turns the other.

i know and i want to rid of the crappy rubber belt and got to a soild chain. better performance

Rubber belt is better performance. It has less weight than a chain so uses less torque to accelerate it. It doesn't transmit as much crank vibrations of pistons going up & dowm to valve train.

Competition Cams has even started making a belt setup for dirt track Chevy V8s.

The down side is that belts are fragile and short lived compared to chains. They also tend to break down with exposure to normal engine fluids. I can understand why one would want to switch to chains.

It'd be nice to have a timing system that would reliably last 160k or more like the timing chain on my Quad4 motor. The Quad4 uses a double row chain that's heavier than a belt but lighter than a v8 chain. Then again the Quad4 puts more power to the ground so the loss of torque due to the chain is less obvious or at least that would be the logical extrapolation from Drews comment above.