I recently bought an M4 with the pistol grip stock. I managed to put in a preorder on Benneli Parts for separate butt stock and pistol grip, which I'm told will work with a 4-postion recoil tube within my stock to net the LE stock equivalent. What you have built is pretty close to what I'm shooting for (pun not intended).
Wondering how I might come out by buying yours changing out the stock, and selling mine.