It all sounds good to me. Some may suggest a different nitro content but that's really not necessary. A nitro content of 30% is a hot and respectable mix. In fact, just to get a little more longevity out of my engines I run 20%. The important thing is to use the same fuel all of the time as your engine is used to running on the mix you've used from the beginning.

Thje MC-9 plug sounds like the right plug to use, especially with 8-port Hyper .21 and the 30% nitro content in your fuel.

I used to have a link to a site that explains plug ranges in combination with different formulated fuels, but can't seem to find it at the moment - sorry...