I see now you have AFR's. I'd back off the torque to about 15-18 ft/lbs. It doesn't take much to strip out aluminum threads with steel bolts, especially the end bolts, they don't usually have as deep a threads as the others and it doesn't require that much force to keep the intake in place.
Twenty is about right and do it from the middle out as mentioned. One suggestion, go through the process starting at 10 lbs, then again at 15 lbs and the last shot at 20 lbs. Then after she has gone through the heat cycle several times, stick it too her one more time. Then you are ready.
I put teflon sealer on the end bolts as they go into water jackets. I torgue to twenty lbs in two steps, then check it again after a heat cycle. The gaskets will squish a little. I too have aluminum heads, but Edelbrock uses steel thread inserts, so I didn't bother with anti-sieze.