Personally, if this was my bike, I'd give up on the engine and use it for parts, you may find that the process of buying individual components will eat up your money and you could have bought one that runs at a much cheaper price

Having said that, if you're going to persevere on, there should be no fuel coming out of the overflow, I was going to say oyu have a float height issue initially, but based on the condition of all the other stuff I would say check your carbs first. Crack it open and see what it is like.

You should be able to buy a pulse generator on its own.