I had flanges fitting to the exhaust laser cut and welded them to the turbo (after cutting away the original turbo flange).
You need Ni (welding sticks?) to avoid cracks.

Have you ever tried to operate a vacuum actuator? If yes the biggest step for a VTG is done. My buddy still works on an independent VTG control.

A final upgrade could be larger elements. We are right now figuring out the swap and adjustment for the 606 IP with e-governor.

Tom