it only has to pass emmisions for the '79 Model year, which is the same emissions test as '76, cat converters are mandatory, put them on every 2 years. if the intake is original and it is non emmisions, that will pass. another option, is get a newer 305 that will pass emmisions, put identical headders on it and then when testing comes around, it only takes approx 45 minuites to change out a small block if you have done it b4.