hey guys, jim here. i am running a 390 gt engine in my 69 torino, its got a healthy cam in it, edelbrock alum intake, 750 holley, headers, gt heads, etc. the engine runs out nice and strong. i can buy a good running 1970 429 thunderjet for a very good price and was wondering if i basically do the same thing to the 429 as i did with my 390 ( cam, headers, intake, carb, good distributor,etc) if i will be any further ahead performance wise. i know there are more cubes and slightly more torque with the 429 but it is also a heavier engine. i would love to swap out the 390 but i dont want to waste my time if its not going to pay off. what do you guys think? thanks, jim.