Todd's sure fire blower sale - Fred,

[Dave Williams]

-> Roots blowers?  If you're going to drive it
-> with a belt, get some type of screwcharger
-> or vortech...   (or Eaton?)

 You're talking about a situation where Dave's Law applies.  $1000-ish
for an equipped 6-71, $2500-ish for anything else.  Also consider the
centrifugal and screw compressors aren't quite big enough for a big
block; to get adequate volume you need at least two of anything but the
largest new centrifugals.