350 wont start

[1968CHEVYC10]

My truck wouldn't start the other day. I traced the problem to no spark, and a bad dizzy. I had another distributer laying around so I swapped that in. Noe I have spark, but it's still not starting. When I tried to start it it would just crank and make no attempt to fire. The carb was in need of a rebuild anyway, so I took it apart, cleaned it up, and put a rebuild kit in it. Got it back on, and now the same results but every few seconds it'll blow fuel out of the carb. I'm kinda stumped as to what it could be, maybe the timing could be off? But you'd think there'd be some kinda backfiring going on if that was the only problem. Thanks yall.