Hi Mark, and welcome to the forum. I live in the NW side of town, if you need any help, or just want to shoot the bull. I did the EFI conversion (TPI) on mine a couple of years ago, so know a few of the pitfalls.
Mark , in case you are interested but did not see it , the Sept. 2012 issue of Rod and Custom Magazine did a nice , informative story on installing an Atomic EFI system using the recommended MSD HEI Modules . There are numerous photos and tips in their story and was an interesting read . Not sure if you subscribe or if the article is available online but their address is www.rodandcustommagazine.com . If you cannot get to the article , PM me soon and I will cut out the article and mail it to you . This should be a great upgrade to your 502 and only wish I could get a ride in it !