Well, I'm the guy with the 5.2 in the TJ. Did it in a long weekend....cost about $600 including engine and trans. All stock parts, including driveshafts. Only aftermarket piece is AA motor mounts. Gets between 25 and 27 mpg on the highway. All stock gauges work and drives perfect. Have over 20,000km on it since swap. But hey, if you want to buy expensive adapters and have a big PITA doing wiring and gauges, go ahead and put in a Chevy motor. Oh yeah....my 5.2 will smoke the tires for a block.