Yes the rockers were redone when I did the intake/Carb swap guy helping me said we should and he did, the intake looks like it sealed OK but it only been run for a total of couple minutes, everything is dry and yes I used the correct felpro gaskets

Where's the timing set at?Like Jay said though check the firing order 14836572(IIRC)

OK didn't want to guess so I took off the valve covers loosened the rockers and I going to do them over again, I removed the spark plug and bought new ones, a few of the old ones had strong gas smell, could the rockers being to tight cause this? And how can I tell for sure I'm on compression stroke?

Got it back together, the popcorn sound was deff the rockers, I redid them and it fired up no problem no backfiring, still needs to be fine stunned though, jay if your around my area anytime soon pass by...