Who makes barrels for M-A1's??

Unfortunately, very few companies are interested in making products for our guns. IGB Austria might be able to work something up for you, but expect that to be an arduous process. The extended barrel should be doable and once you have it, it shouldn't be too hard to find someone to hack it up the way you want it; the compensator would need to be a completely custom thing (we've never seen it done beyond thread-on stuff).