super six or 4 brl?

well... im having better luck finding an affordable 4 brl intake and carb. im not a slant guy so im not going to argue, im lookign for info, but in theory i dont see why a 390 wouldnt work fine on a 225. primary should be smaller than the super six and secondarys will only open when your on it. whats is the super six carb 280 cfm or something? i cant see 100 cfm hurting, especially with a header. the header will flow better than a cast manifold, and im going to do a single 2 1/2" system if i do either swap. only because i have left over pipe, mufflers, glasspacks, and madrel bends in the garage right now. i guess i could port the head. are different year heads any better?