does anybody know what kinda horsepower gains are to be expected with the lt4 conversion package and what ratio rockers come with it?

 

According to www.paceparts.com up to 425 HP... It comes with 1.6 GM roller rockers ( made by Crane).....

 

I have the kit with ported stock heads. For a better cam then stock this is great. If you are serioous track person then bigger is better but its good for drivability and fun to drive. For the money worth it. As long as you get the stuff you need like good head work and exhaust.