I bought the Ultimak. Here are pics.
very satisfied and very good customer service. very solid > it mounts with 4 screws at front and 2 screws at rear. No drilling/tapping.
I bought a .83" riser in case I want to play with a 3X magnifier but probably not. From what I see, you have to get close to magnifier like with a scope. I think the setup is too far from my eye. The riser has a square hole for seeing the iron sights. If you need a riser, shop around, they are not all the same. Many have 1 screw hole is also the crossbolt to keep the riser in place. I found a riser with 2 screws and 2 crossbolts. The crossbolts don't go all the way across but they securely fit in the grooves. Amazon for $9.00.
Thank you all for your advice.