John,
If 2x4 has worked for you before, it should work again, BUT a 2" pin position will make the ball hook earlier than a 4" or 4.5" pin position. A 2" and a 4.5" should roughly have equivalent flare. Actually, since you can easily plug and re-drill, I'd suggest, to decrease early hook , maybe you should start with a 4x5, pin under bridge, with a 2-3" pin ball. Pin on one side of the centerline, CG on the other. This is a dynamic core so the final side weights make less of a difference than with pancake core balls. If you don't like, plug it and redrill 2x4.
That weight, for 30+ years. OK, health and knees problems.
Lose some and you'll more easily be able to throw it faster. I am not light weight, so I know where you're coming from. I prefer medium speed but can hike that up if needs be. 6'5" is good; 280 is over the limit. Try only 20 lbs and see how you feel. Then you can try the normal add-speed-by-doing-X routines.
Honestly.
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"Just because you can do something does not mean you should do it."
"No good deed goes unpunished."