So here's what I got, two half-inch thick plates of steel.
One bolts to the manifold.
One bolts to the turbo.
Then they bolt together.
I had home-made tin gaskets in there with plenty of copper goop, and I think they were sealing good enough, until the top two bolts holding the adapter plate together started backing off. At one point there was like an 1/8" gap between my adapter plates. I don't think it ever sealed back up after tightening. I think I'll need to use some thread locker or lock washer in there next time.
But also, the adapter bolted to the turbo is super pitted, much more than I remember. So I think I'll need to get some new plates made for next time.
Any machinists out there want to make me new plates? These were the prototype, I know how to make them better next time.
Or if anybody has a better idea I'm all ears.
I also bought an 1/8" thick piece of copper plate to use as a gasket in between the two plates, instead of my tin gasket. I'll see how it works. (So far, I think I should've bought a 1/16" thick piece of copper.)
I also have no idea how I was going to groove things. Not enough space in between bolts to do that, wouldn't have worked, unless I put the groove way around the outside.