I believe this will probably work out fine but I'm wondering if I will have created a mismatch.  The barrel on my AR is a Rainier 18" 223 Wylde Match with a mid length gas system and a gas port diameter of .085" ( + or - .002").  I will be replacing my pinned Magpul MOE stock with an Ace Skeleton fixed rifle stock using a standard A2 buffer, A2 spring and A2 receiver extension.

 

Like I said, I'm pretty sure this will be fine but as they say....  Measure twice, cut once.

You should be fine. My midlength 18" barrels are similarly sized in the gas port and they cycle an A2 buffer without issue.

Worst case, you open the buffer and replace one or more of the weights with 1" dowel or equivalent.