air or fuel, what am i running out of

I had an old 318 with170k miles on it I put in my dart just so I could ln drive it. Stock 78 short block, untouched except for a new oil pump and old 20 yr old crane fireball cam. Added some old Engle valve springs, single 28th dampers. Stock 69 340 intake and Holley 600 28th choke removed and k&n stub stack and Headers. 4 speed and 3.91 sure grip. Very reliable and strong. Added 1 inch 4 hole spacer and noticed BIG seat of the pants difference.