This is a pretty good post thanks.
IMO the only other single pass worth buying is the 2-149 off a 63-65 Ford FAIRLANE pictured below because of inlet/oulet positioning on face. a bit smaller than the 2-342 but it may find a home because of that.
This link below is a pretty cool. Not everyone carries Fedco cores so just enter the number you want and it tells all the compatable cores from different manufactures.
http://www.autopart.com/radiatorinfo/heatercoretech.htm