I have only one problem with you'r situation.
Try taking the MAF completley off and run the engine, it still runs only the CEL is triggered.

Or keep it connected to the harness, but simply put it aside and remove the intake tube (leaving the TB open). It will still run.

That's why i don't think you have problem with ari/fuel ratio.

Than again you put the stock MAF electronics in to a bigger housing, right? So why wouldn't it work.
It dosn't realy matter how big the oppening around the sensing element is, because it's in the center it's not rading the "amount" of air going through it, it reads the speed of the air.

Try measuring the output using a tester and blowing on the element, the stronger you blow the higher the output (or less or more, can't remember, the resistance will be).