With garcia on there it's bound to work great. Nice tribute mash tun.
If you continue to get leaks, get a second red rubber washer and put it on the inside of the tun. And, make sure to use thread tape on the nut on the inside of the tun, on the ball valve.
I'm not sure of your connection intensions, but I can tell you from experience that that barb would be better replaced with some cheap brass quick disconnects from McMaster Carr. Let me know if you need part numbers.
Curious why? What would you ever connect to the barb other than a 2-3 foot length of tubing?