In my experience the big glow engines run fine if you have the tank right behind the engine.
The problem being is that the big thirsty engines need large tanks if you want to fly for more than 5 minutes; when you run a large tank (over 20 oz) right behind the engine the airplane is so nose heavy at the beginning of the flight that performance suffers. (anyone that says it doesn't is obviously not an experienced pattern or imac pilot.) On my moki's I tried using header tanks, both styles of perry pumps. none of that garbage worked to my satisfaction. finnaly I purchased a cline regulator and all my problems went away and I have my 24 oz tank on the c.g.