I moved from CA in 1990 to NW Arizona. No smog checks here. Back in the day when it came time to smog, I would pull my Mallory Dual Point Mechanical Advance distributor and Weber 32/36 DGV Carb off and put the stock Hitachi Carb and stock single point vacuum advance distributor back in. 1 1/2 - 2 turns on the idle screw (Tuning by ear, backing it out from seated until it wouldn't gain idle, turning it back in until the idle just increased, then backed it out a 1/8 turn. It usually ended up somewhere between 1 1/2 - 2 turns out.) and take it for a smog check. No cat or smog pump, etc. on the 1973 B1600. The smog tech might tweak the idle screw a bit and then pass it. Sometimes too lean an idle will raise HC. If it is still points & condenser, I suggest changing to a Petronix Ignitor that makes your distributor an electronic type. No pitting points or gap to worry about. Around $50 - $60. Hope any of this helps!