The engine as a whole is sucking a ton of air...it would literally pull a tennis ball through a garden hose. If you lay your hand over the carburetor and plug it as the spin the engine, it should leave a red ring in the skin of your palm. The only way to screw this up is to mess up the cam to crank timing when you assembled the engine.
I would not focus on any puddling or vacuum issues but would make darn sure I had the engine timed perfectly. I don't mean degrees advance or retard, I mean #1 at TDC when it needs to be. You are chasing ghosts.... get the timing right, make sure the solid state deal is good to go and you will triumph! If this isn't the case, I will drive to MD and paint your house with the color of your choice. I have made this offer before and never had to take paint brush in hand.
If you can work on a Mercedes, this old bolt should be a no-brainer cake walk! I'm assuming that's what Benz Dr. is all about!
Herr Mueller!
