I would get a large fan that is at least 17" in diamater like a standard box fan, and mount it in front of the radiator. for a temp gauge you could get away with using a radiator cap with a thermometer on it, they sell them in summit, 6lbs-16 lbs I think, for around $20. as for a starter button, any momentary automotive grade switch should do, a 10 or 20 amp switch should do, if you want to go hi tec, you could order 1 of the ign panals from summit with the on off toggle switch and the rubber coated push button mounted on a nice aluminum panal as for the 10 ga wire, that will be plenty. as for the heat of the exhaust , I know there is heat resistant stuff you could use that will work, maby even wrapping the tubes in headder wrap, and then using a heat resistant insulation around it going thru the wall, maby like what they use to insulate furnace chimney's with ( the steel chimney's ), they get pretty hot, along with the headder wrap you should be good. and if u need quiet, get a stock muffler or a turbo muffler, they quiet up as you rev an engine up. and for fuel supply, an above deck portable fuel tank would work good.