I bought a used lo miles set of 1.9 Performers and they had come off a 302 so had the bushings in the holes. I was putting them on a mild 351, so just knocked the bushings out for the bigger 351 head bolts.
You still have to use the bushing kit. I had the same question and emailed Edelbrock with that answer. Unless your running 1/2" bolts you will need the bushing kit.
Final torque specs according to the instructions that came with the heads say 80 lbs on the long bolts and 70 on the short. Torque all bolts in sequence like normal to 70 lbs-ft and then torque the long bolts to 80 lbs.
I use motorcraft AGSF32C plugs in my edelbrock heads. I think it is about the same as a autolite 24. My car runs better w/ a little colder heat range plug.U still got to use the bushings cause these heads also fit a 351 and it uses 1/2in head bolts