How is your smog test calibrated.
Our air care test they check NOx, CO and HC. This is done at idle and at a sustained speed of 50 klm/hr over a certain time period. Usually if you fail it will be on 1 or 2 readings unless your engine is totally hooped or you you have major emmission controll problems. If you only failed on a couple of things it could just mean things need to be adjusted a little. Things that can cause bad readings are wrong timing, too lean or too rich mixture. Engine not hot enough, leaking vacuum hoses, stuck EGR or PCV or burning excessive oil. I have a 240 with tripple webbers and absolutly no emissions equipment at all and it will pass with a stock cam. I have had a real go of it lately, trying every trick I know to get it through (and I know a lot of them) with out putting the stock cam back in. I finally bit the bullet and put it back in today. If it doesn't snow tomorrow I'll go through the test @ $24.00 a hit it gets expensive but I can't get insurance till it passes.
Find out why it failed and on what readings and I can give you a better idea what to try. I would assume that your test and our test are more or less the same. Ours is apparently modled after the one in California.