slant 6 to big block

Hey everybody, just got a 68 dart 270 slant six for a good price because I want to make my own street beast. I want to make great power on pump gas (92) octane, and I would like to do a big block. Anybody out there got any suggestions for what I could do to this car? (Kinda wanted to do a 440) As far as which big block would be good for fitting and stuff? Any info would be very much appreciated. Thank you