Man, this is a tough one. The lack of intake manifolds for that engine really limits your choices. It looks like only Weiand makes an aftermarket intake, and it's not a blower manifold. The only superchargers that will work with the stock carb and intake are the centrifugal ones. Vortech Engineering has a Universal Small-block kit. This is for chevy, but it looks like it could be easily modified to fit the poncho motor, or anything else, if the pulleys lined up. Vortech sells a lot of pulley kits too.
Here's the description on the Vortech site:
http://www.vortechsuperchargers.com/...l_block_1.html
These people sell it:
http://www.superchargersonline.com/p...r=V4GP218-010S
The cost for a new kit is frigging enormous of course, but a handy guy could probably get a used vortech blower on e-bay, fabricate the ducting (it's just some aluminum pipe), and just buy the Vortech carburator enclosure alone. It's about $675 here:
http://www.vortechsuperchargers.com/...carb_encl.html
I bet you could piece this together for about half the cost of the kit. It won't look as cool as a big roots-type blower, but without any manifolds you can't put one on anyway. I can't think of any other way to do it. Good luck!