I have been on a chassis dyno 3 times. It's best for test & tuning, not absolute power of the engine since drive line loss is anywhere between 10 and 20%. Torque convertors totally skew the output, so I would not be trying for best effort. If however you're going for a best effort number, make sure your fuel filter is clean, fuel pressure is adequate, and your timing is correct. Slicks also hurt, use radials if possible, a 3.08 gear has less friction than 4.30 so swap that, carbon fiber driveshaft and light weight wheels of course...