52degrees, thanks for the idea! I tried out some numbers using this online calculator http://www.smogsite.com/calculators.html#lambda

I plugged everything into the calculator and here are the Lambda values I got from the smog checks mentioned above along with the complete smog data.

EMISSIONS CHECK SUMMARY (15mph/25mph)

Test 1 :270 cam, old cat
HC(PPM): 206/225 avg43/32 [color:"red"]FAIL HCs[/color]
CO(%): .63/.62 avg.16/.15
NO(PPM): 719/725 avg406/349
CO2(%): 13.8/13.8
O2(%): 1.0/1.0
Lambda: 1.021/1.020

Test 2: stock cam, old cat
HC(PPM): 198/181 avg43/32 [color:"red"]FAIL HCs[/color]
CO(%): .64/.60 avg.16/.15
NO(PPM): 934/815 avg406/349
CO2(%): 13.6/13.6
O2(%): 1.1/1.1
Lambda: 1.026/1.028

Test 3: stock cam, new cat
HC(PPM): 35/18 avg43/32
CO(%): .03/.01 avg.16/.15
NO(PPM): 25/16 avg406/349
CO2(%): 14.3/14.3
O2(%): 0.8/0.8
Lambda: 1.035/1.037

So it appears the engine is running on the lean side, but I don't know how to interpret the magnitude of leanness.

Please let me know where you think I should go from here.