With what you have, I would simply swap the MP 292/509 with a Comp Cams Magnum 292. It's the same rough specs, but much more street friendly. Including tight (low stall) convertors and gearing. A couple of notes, a 12 second Ebody needs about 400hp. To run 11s, you'll need a bit closer to 500. Torque gets a car with 3.55s moving, and you better have the tires and suspension to stick them. You have no idea what the compression is. You used pistons taht were rated for "10:1", correct? That means if they are typical, you really have about 9.4:1. If you want that snap, you need to do a little mroe homework to see where you need to make up. A simple check, take a compression reading from every hole, with the engine hot, and all the plugs out. If it's under 130 with the MP.509, you dont have 10:1, or the cam is ground retarded (standard Operating procedure for MP stuff... poor execution, good theory... A cam swap will make you happier, but bigger is not the answer. Better is. Also, on valve springs and what you "can run"... some .550 lift cams need hevier springs than what Edelbrocks come with. The more modern the grind, the more spring it needs, and the more likely you'll be removing the original Eddy ones if you bother to look. What you have will work with the Comp 292.