Plumbing to shower head question

[zeebies]

Need some plumbing help please. I’m trying to get my water change system set up in a spare shower. I need to replace the (almost impossible to turn) valve on the left side of the old shower head:



With this:



The hose on the top pic is 5/8” OD. GF valve below is 1/2” and threaded inside.

System in progress:



The GF valves turn like butter…

Any suggestions for what fittings I need are appreciated. And links to parts would be amazing.

 

[wvned]

I would leave the old alone. Screw a barb into the threaded part of the new valve and cut the vinyl and hose clamp the new valve in it.

or get a push to connect stub to 1/2 in threaded. These are available in straight and 90s and just replace the valve.
They have the stuff at Home Depot

or

and use a short piece of tube into the 90.

 

[zeebies]

I would leave the old alone. Screw a barb into the threaded part of the new valve and cut the vinyl and hose clamp the new valve in it.

or get a push to connect stub to 1/2 in threaded. These are available in straight and 90s and just replace the valve.
They have the stuff at Home Depot

or

and use a short piece of tube into the 90.

Thank you wvned. I will try your first approach as I have been overthinking this.