From 6 to 8

Motor mount setup (which allows you to bolt up a v8 to slant 6 k frame) or buy a v8 k frame (73+ spool type is the best), v8 tranny either auto (904 or 727) or manual (833 non-overdrive the way to go) and depending on the power output of the motor a stronger rearend, either a 8.25 or 8.75 or Dana 60 (over kill for a normal street with about 500 hp or so). I suggest either a LA block (pre mag) 360 roller motor or a 5.9 magnum be the best way to go. That or you could always go for a new hemi 5.7, 6.1 or 6.4 motor.