I don't know if this will help, but I have a E7TE roller block with what I think are E6 heads, and I had a problem finding plugs that worked. Summit helped me decipher the plug and they said I needed the AWSF44C 14mm thread, .708" long reach tapered seat plugs. The engine is still on the stand so I can't speak to how they work yet, but they threaded right in, and they don't hit the pistons (yet).
Pay no attention to the yellow intake as it is a dust cover right now. Lol