Why not quit this foolishness and use the real thing if realism is the goal...
http://preamps.ru/jcm800floor2.html
http://preamps.ru/index.html
Use Chrome to translate the above web pages!
Arthur is a Russian guy who's been living in Bulgaria for many years, with good English skills who builds high quality - high voltage tube preamps of many kinds, plus he does custom work as well (I have two, JCM 800 and Fender Twin, both perfect and accurate to the real deal).
Arthur Sounds JCM 800, a true high voltage JCM 800 in a inexpensive lightweight pedal, and then use that L6 modeling gizmo for a tube power amp sim assuming that's possible with a L6 (QC and Axe allow it and it's awesome, real tube tone without the weight and SPL limitations).
You can't get realer than the real thing LOL!