Recommend holding out for a mated lower or upper from one of your two manufacturers. Due to the non-standardization of AR-10-type rifles, you should mate uppers and lowers only from the same manufacturer.
You could also just fucking do it and post pics.
Your BCG will not suffer any nonstandard wear and tear. Buffer system length has virtually no effect on AR-15 operation (buffer weight, however, does), aside from barely perceptible differences in cyclic rate if you use a rifle tube buffer spring (which, depending on your spring system, you need not do).
Your rifle-length buffer tube will have a far more dramatic effect on ergos vis a vis your more limited buttstock options.
https://s1.qwant.com/thumbr/0x380/1/6/8fb72e97c71aabc1e09756602a7c44ddf1a84692b6d412c60a4509ab2fe3c8/c7c1648ec0e7636e057ffaf9cfed8b46.jpg?u=https%3A%2F%2Fi.pinimg.com%2Foriginals%2Fc7%2Fc1%2F64%2Fc7c1648ec0e7636e057ffaf9cfed8b46.jpg&q=0&b=1&p=0&a=0