Fuel injection using low-cost salvage yard GM "batch fire" components ought to work basically the same as for the slant six ( or any number of other motors). Try the link to the slant article, there are several current message related to this topic on the message board at that site.
Depending upon your skills in fabricating parts such as the fuel rail, EFI should not be too costly, the parts are common in pick-n-pull type yards.
http://www.slantsix.org/articles/dibiase_efi/efi-conversion.htm
