If a 'Samsonite' delivery is all you can do, then by all means do that. Here are a few things to keep in mind;
With your thumb at 9 and your fingers at 3-5, thumb and fingers will exit the ball very close together. The result will be more skid and fewer RPM's. While you may get a 5 board move, what happens after that move is what's important.
The movement is the result of weight block position, axis rotation (90 degrees), axis tilt (?) and ball speed (?).
I'm 69 and I also run into wrist problems. I do just the opposite. When my wrist hurts, I wear a glove when I bowl and I also wear it at night when I sleep.
I try to release my ball with as little axis rotation as possible. Thumb at 11-12. I get my ball down-lane with forward roll, not skid. This method allows my delivery to 'store' whatever energy I imparted as far down lane as possible.
The final piece is a relaxed arm-swing. I mean 'very' relaxed. If you relax to the point that you never pull your hand through the ball, you may notice that whatever pain you feel may be reduced. You may also be surprised by how many RPM's you get with less effort.
I think a 'Samsonite' is a very weak hand position. Thumb at 11-12 and fingers at 6-7 is much stronger, but must be combined with a relaxed arm swing.
15 lb Storm Hy-Road : 65 x 3-3/8 x 25 500/1000 Grit
15 lb Storm Hy-Road : 50 x 5 x 50 Polished
14 lb Ebonite Cyclone : 50 x 5 x 50 Polished
15 lb Columbia Blue Dot: Circa 1978
325 RPM'a @ 16 MPH