The ECL86 is 2 tubes in one. It's basically an EL84 power tube with a single 12AX7 triode in the same case. Hammond used them as a space saver in their AO44 reverb amps. There's several conversion schematics floating around the web for those.
One amp circuit that comes to mind which would work with that tube compliment is a Marshall 1930. They used a pair of 12AX7's and a pair of ECL86 tubes. Dump the EZ81 rectifier in favor of diodes to free up some heater current to power an additional 12AX7 and you're good to go.
Here's one:http://www.bolimbo.dk/guitarer/forstaer ... opular.htm
There are a few 18W Marshall circuits that used ECL86 tubes and the EZ81 rectifier too:http://www.drtube.com/library/schematic ... mas#JMP18W