Move as much of that weight as you can, forward. I relocated my two TM batt's to under the CC (about 4') and it helped how my boat handles a LOT.
But in selecting the right prop, you'll need to know what your RPM's are. Without knowing that, you will just be guessing. Propper motor setup is also a factor, and something that should be addressed before you buy a prop. My advice is consult a true prop guru before you buy anything. Steve's Custom Props in Emory, Tx are just that. They build their own line of jackplates (rapid jack), and do custom prop work as well. They don't just sell and repair props, they assist boaters in achieving the optimum setup for their particular rig and its use. If that means taking a new prop and adding cup or rake, then that's what they do. These guys know their stuff. I'm not affiliated with them in any way, but am a satisfied customer, along with anyone else I've talked to that's done business with them. It certainly can't hurt to call them and talk about your rig.
With a tunnel, I'd want a jackplate for sure (you don't mention having one now), if for no other reason than to take advantage of the added clearance you can attain, then comes selecting the prop that optimizes that setup.
All that said, tunnels are not known to be speed demons, and with a 50hp motor on a tunnel hull 1860, I doubt you are going to see any massive gains in speed over where you are now. But stranger things have happened.
Keep us posted on what you do, and the results of that. I had SCP setup my old glass BB, and saw some significant improvements in every asoect of handling and performance. Running that boat skinny was never a concern, but I did gain some draft as well. I haven't taken my Xpress to them yet, but need to stop procrastinating and do it. My Xpress does OK with factory rigging, but I feel there are some noticeable gains to be had on it too.
