Here is what I would do.
Nr.1 Check your compression on all cylinders if above 100 PSI good.
Nr.2 Check to see if your choke is working.
Nr.3 Mix a spray bottle with fuel/oil and give the carbs a good dose and crank her up.
Hopefully she will fire up and stay running,if she fires up and dies,it might be time to clean out the carbs,check the fuel pump,and check your fuel lines all the way back to your tank including you pump bulb.Any leaks air or blockage will cause her to die out or run crappy.Since you say you have good spark these are the things I would check first.Check back let us know,you will find plenty of good advise here to get you up and running.