No model, no year, no engine size, sorry I can provide no answer with just Chevy to go on.
1-6-5-4-3-2
18436572
1-8-4-3-6-5-7-2 for a V8
1, 8, 4, 3, 6, 5, 7, 2, clockwise.
If your distributor is in the right place.The firing order is 1-8-4-3-6-5-7-2 and it goes clock wise on the top of the distributor cap