That does look good. The tib barrel is a bit more complicated to create this for though. Unlike most barrels on the market it doesn't thread on, it has a groove cut along side that slides over a pin allowing it to turn up for a hopper or down for a mag.
It has a thicker sidewall for this, which makes milling easier, but the groove could be an issue for tolerances.
I saw that another airsmith was trying to create something like this and gave up on the pursuit. I'm not sure what problem they actually ran into though.