Short, you can work with. A slip on pad works for me, but, you could go with a recoil pad as well, whatever works for you. When the gun has too much/too little drop or cast is when you have to think about throwing in the towel to find a different one that fits.
For reasons I can't even begin to speculate on, a high percentage of the people I know who like and use a Darne also have a pump hanging around. Weird, but, having said that I fall into that catagory as well.
Use your Dad's old gun in good health.
Best,
Ted
