I agree it sounds like the timing, to double check bring #1 up to TDC and check that the rotor is pointing too or firing #1. You did adjust the valves if unsure recheck. Thinking outside of the box for a moment it could be an intake not closing. I say this cause you indicate you just put the motor back together so I assume you had the heads off. On the other hand if an intake was the only part swapped, timing is it just sort that out and you will be golden.