No start on rebuilt 360LA

Also you have not stated if you have solid lifters or hydraulic lifters. We see you have adjustable roller rockers.

If you have hydraulic lifters and your oiling system pumped up and primed. On compression per cylinder set intake and exhaust lash to 0 lash (Zero lash) then one half additional turn to preload the hydraulic lifters.

On solid lifters set intake and exhaust to .018 ths valve lash up on compression stroke per cylinder.

Having the valve lash set too tight will keep the valves open and will cause backfiring upon ignition.