I ran AC R45TS plugs in my '72 307 motor. If your heads have tapered spark plug seats you can use the above plugs. I don't see a problem with running them with the HEI. Maybe the gap can be slightly larger w/ HEI.
10-4 on the 14 AWG from the distributor to the switched side of the fuse block
I will be off to Pimp Boys tomorrow to look for some AC R45TS or maybe some Dinso U-Grove or anything i can fine that is in the heat range of a R45.
By the way is a 43 hotter or colder plug?