if the heads your talking about are the vortec 96and 99 heads they are a good head and can be made to run just did a stock 99 vortec with vortec heads some small tricks i do in side the engine as i remachined the engine .customer came by .i took his truck for a ride runs good for what it is .trans was hitting to hard for me to get on it to hard i think line psi was to hi ? i have seen the peanut ports work good to for max TQ at low rpm it.s about what your you want out of the engine. i just did a set of the 454 vortecs that i cut out for bigger valves 2.250and 1880 and alot of bowl work on the tobin arp with custom cutters . this set of heads are going on a V drive boat in a 600 cid 11to1 with a tunnel ram small rollercam solid 680 or so lift this was the only heads he had at the time we are betting on great TQ numbers with killer mild range . we are taking bets on were the heads will nose over but with the right gear he will max the hull out before he gets to where the heads stop working .i would not pass by this head for a pro comp heads. a set of darts or afr yes