At your performance level, an inducer should help everywhere, but mostly out of the hole. Best to machine the shaft while it is apart.
Did you have a porpoise with the full-droop? I'm curious how it will perform with the HPH over the full-droop. The HPH is really a nice part, but if you have the power to take advantage of of the full-droop, you might see a speed difference.
Did you get to ski behind it already? I wonder if you will see a difference in the quality of the wake.
Detailing the front of the impeller would also really help on the hit, followed by detailing the bowl.
Stuffer wouldn't hurt, but if you are on a tight budget, do that last.
The only things you can't do without total disassembly are the shaft, thrust bearing, and inducer. And double drilling the suction if you feel you really need it. Everything else can be done after installation.
Cheers,
Joe