well, if you have any of that stuff left, try a mix with 20% gasoline...
like 3 Sunny + 1 gas +1 Castor,
and see if the hotter runs lead to unlit plug working.

I cant really see a way for me to try a cooler run with the e85.
Even so, at this point I may have to buy a IR thermometer if I am going to investigate the temps.
Running hotter is as easy as blocking some of the cooling fins,
but I wouldnt want to try that without being able to keep a better eye on the temp of the head