Easiest way to plumb would likely be to cut off the fitting on your current lines and reflare with a standard thread fitting, as long as 3/16" tube fits that master. (3/16 is a close enough match to the metric tube Toyota uses).
All you need is larger bore M/C to match the larger bore of your 1Ton brakes, doesn't matter whether it is a chevy or Toyota one. I want to say the largest Toyota bore I've heard of is around an inch. A buddy runs a E350 van master on the buggy below with a D60/14b, stops great.
That adapter plate looks pretty simple. Don't need CNC to make that. Still, $95 isn't bad.
Let us know how it works.