Might be luck of the draw, but, when hunting for the (9447-combination metal and gasket, egr baseplate gasket) that goes under the (9A589-egr spacer) the parts houses have a hard time finding it or coming up with a number. They will bring out the thick (9C477-thick gasket) or the thin one.
Also the thick phenolic spacer numbers.
When doing the 2150 feedback to regular carb conversion that a lot of people do, you have to change that also.
I ended up modifying mine. I roughed the side up, then drilled small, short holes and pressed pins in the side to hold the hard, machinable, ribbon type epoxy. After hardening I re-surfaced both sides. Run what you brung.......
And as far as stacking, I am not sure about whether you are supposed to have a thin gasket on either side of the thick gasket that goes on top of the phenolic spacer. The thick gasket has plastic bushings in the mounting bolt holes to keep it from being squeezed very much so I don't know if it is sealing completely. I don't remember if I used any thin ones as by then you are running out of space to put the nut on.
Dang! Kinda long winded...Guess I don't need any more coffee this morning!
Thanks again for your work!

 

I've put two pages up regarding your question, and while they are far from done perhaps they will help:

Gasket: Carb/EGR to Intake (9447) - Gary's Garagemahal

EGR Spacer - Gary's Garagemahal

 

Interesting that they do not show the combination phenolic spacer and egr spacer and thick gasket used simultaneously.
Also interesting that no thin gaskets are shown......
I guess if you use the combination that no thin ones are used.
Or maybe a thin one between the egr and the phenolic.
Your thoughts?

 

First, don't put a lot of faith in the thickness of gaskets shown in the illustrations. The drawings are just to illustrate where the part goes and the basic number that goes with the part more than exactly what the part looks like. So there may well be some thin ones in some applications, but the same drawing covers many applications.

And, it has been too long since I worked on a 2bbl engine for me to remember the gasket thicknesses. So, I really can't say - right now. However, NumberDummy is going to call me later today and I may have better answers afterwards.