(Before the current freshen-up in progress)
440/+.040, 9-1 compression, RPM heads and intake, 850 demon mech. secondary carb, carter street fuel pump, 274/286 cam (230°/236°@.050), 1-7/8 headers to 3" exhaust, 2500 stall, 3.73 gears, 3650lbs with me in it. 800 rpm in neutral, 700 in gear@16 in. vacuum. Dropping 400+ rpm going into gear from a warm idle is too much for me.
I will say, I'm not a believer in the 'vacuum secondary only on the street', but that's only for my own experience, everybody's is different. I believe the reason that came about was from people slapping holley double pumpers on mostly stock cars back in the day, and there would be a bog when you floored it--too much too soon. With the adjustability of the carbs today it takes a little extra work but you can have a great running mechanical secondary carb on a street car if everything plays well together. Progressive linkage is a must. Mine doesn't bog, burp, fart or run too rich..but oh boy it's much easier to get your foot into it, thus a little worse on mileage if you're not careful (and who's got time for that lol!)