MSD and Pertronics both make commercial conversion units, but I prefer Dave's Small Body HEI. Dennis (DJD on this site) turned me on to him. He has a web site, which I think is DavesSmallBodyHEI.com. Not sure, but google will find it. His uses parts you can buy from NAPA, in the event you get stranded. I had a Petronics unit on mine, and switched to Dave's. Only problem is he has to machine the underside flat (it has a slight taper from the factory) so you shouldn't use your original distributor. I bought one on ebay for $5, but If you don't have an extra, I'm sure you can find one at a junk yard pretty cheap.
As for the wiring, you should run a full 12 volts to the coil. On original or repop harnesses, the resistance wire and the yellow wire are on the same connector. I removed both, and "Hid" them in the wire tray. Guess what, The car wouldn't start!!! The yellow wire goes to the coil to give full 12v at "start". Without it, you only have continuity in "run" duh!!! Put the yellow wire back on, and it's fine!
I run the conversion, and keep my 499 in a safe place.
:beers: 
