i need help on where to start! (carb setup)

thanks for all the responses. i dug out the old 650 holley from last year and it started immediately, ran for about 6, 7 seconds and died. it didnt even try to restart...didnt even pop. i tried pumping the carb after cranking a while after it died. nothing. my initial timing was at 20* for all of this. i will follow all your suggestions on the 750 but now im almost thinking ignition...i have spark and it wasnt flooded when it didnt restart. and i know it had fuel to the carb after the swap because the accelerator pump was working. oh and comp told me to lash at .008 so thats what i did...could that be too tight? would extremely low compression cause this issue as well? im sure its something simple and stupid but for now im still confused...ill get back to you guys with more info when i have it. i will try everything mentioned, thanks