Power loss. 318 Vs 340 manifolds

I know the article that furz4 is referring to which was done by Mopar Muscle. The difference between the 318 and hi-po 340's was not significant (11 or 13hp) which isn't enough for me to make the jump to the 340 manifolds. A guy offered me his 67-69 340 manifolds for $250 and even tho that's a great price, the work required to get the existing 318 manifolds off, the 340's on and ensuring they don't leak is not worth it in my mind. Others might think it is for 11 or 13hp so call me crazy.