Sorry Gary, I'm not going to be much help with paints as I've switched over to Vallejos a while ago.
In my past life, I was a commercial illustrator and did color illustration paintings so colors are kinda my thing. DO NOT add black, black will kill the color and you will get a brown.
I just checked my Aviattic sheet. To get the cherry red you need and on my Camel, I started with a medium red and added Mahogany. For me the 5-1 ratio worked well.

The stripe on the rudder is probably your Tamiya red, the vertical stab is the cherry I'm referring to. Sadly, the camera made that cherry red much brighter in the pics than it is in than real life.
Hope this helps.