How do you know if you have your distributor off 180 deg on a 1985 Chevy 350?

Remove coil wire,

Remove #1 spark plug,

hold finger over spark plug hole,

have someone jog the engine over until you feel compression from #1 hole,

turn engine by hand until timing mark on bottom pulley lines up with TDC on scale,

remove distributor cap,

rotor should be pointing to #1 in realation to the distributor cap #1.