Ignition timing on 305 chevy

http://autorepair.about.com/library/firing_orders/bl-fo-11659.htm -- here's your firing order just in case the wires are not on right.

Pull distributor out, roll engine over 360 to t.d.c. comp. not t.d.c.exhaust like you might have it now.

yes you can be 1/2 turn off with the distributor, remember the piston comes up to top twice on a four stroke! and wires must circle cap same direction as rotor spins! no 1 is usually marked on cap at base of terminal