Tango I was in the same situation as you when I bought my 35whelen. It had the rem. hard plastic buttplate and would get sore as hell shooting 250gr hunting loads from the bench. I was going to put an aftermarket pad on but the LOP was perfect as is and I didn't want to cut the stock.
I remembered I had a simms slip-on pad on my turkey gun. I slipped it on and now there's hardly any felt recoil from the bench. When its time to go hunting I slip the pad off. Not really going to feel the recoil when shooting at game anyway.
I used the same pad on my dads m700 30-06 with the hard plastic plate the other day, Felt recoil comparable to a 7-08. Could shoot it or my whelen in a t-shirt all day long with no shoulder tenderness with the slip-on pad.
Not trying to talk you out of a new gun...we all need more of those
Maybe just a $20 solution to your problem, sounds like a fine rifle ya got!----Gate