Humm ..How long has it been since rebuilt? Built by some one you know? Heads redone?

Lots to look at on something like this..

Is the distributer in and in the right place?

Spark plug wires wired correctly?

How long sinse its had oil? The old fashion squirt some oil in the spark plug holes not a bad precaution..Some would also turn over the oil pump using a drill.

Check for compression? Just because someone re-built doesn't mean it's done right.

Don't mean to scare you..Good chance you'll end up fine..I'd do all of this if I re-built one.

Best of luck..

Keith