[Rev]

My set up is fairly similar to yours except that i run a 3.25 instead of a 3.55 axle. I use TFTW heads and a CC268 hydraulic cam.

Mine gets 14 mpg with me not being very careful. After all, secondaries are meant to be opened aren't they? We don't want the gas in the secondary float bowl getting old do we?

I would run a 180 thermostat for all around driving. I also would just run the stock recommended plugs for your heads. I personally like AutoLite. Don't worry about not enough back pressure. The less the better. You won't need back pressure to make torque.

Rev