You're fighting Newton's law of physics here. With not wanting to use a mitigating device like a comp. you really limits your options. Adding a heavier buffer and stronger spring will only change the shape of the recoil pulse. The heavier setup will cause the pulse to rise faster at the start of the recoil movement where the standard setup will build a little slower, but get higher towards the end. Your only option is to increase the mass of the rifle. If you have the standard A2 style stock, you could purchase a 3# lead insert that is designed to fit the shape of the storage space. I use one when bench shooting. It is really noticeable when you are carrying the rifle and it changes the balance point considerably.
Here is one other option you may want to have a look at. I have one in my rifle because I shoot almost exclusively with a suppressor. It allows you to adjust the gas at the bcg key. I am not totally endorsing this product just yet as I am having some inconsistency in the cycling. It may be that the gas key port being partially closed off causes it to foul quicker. It worked great at first, but over time the action began to slow down to the point of stovepiping cases. I need to spend more time with mine seeing if different ammo will shoot cleaner and not cause the problem. Like I said, you really have limited your options so this may be one of your few ways left to go. Here is a link to the product.
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I forgot to add that I use this bcg to reduce the overgasing due to the can. If you are using it to reduce the normal amount of gas entering the system you will likely have to go to a lighter buffer or spring to keep the rifle cycling properly. Even after doing all this, I can't tell you if this will actually cause a perceived reduction in recoil and muzzle rise. It's an option which is what you are looking for. It's your call if you want to venture down that road.
Some interesting points you brought up their kingfish. Thanks for your post.