You aren't that badly off in the flywheel department.
MANY of us here (my turn hasn't come yet) have converted their TDI DMFs to G60, so there is a mess of DMFs out there that nobody wants. You need one to cut the center out for your new flywheel. You need an old Mazda recip unit (i.e., no counterweighting - or you can just machine the bits on an old rotary to clear off the excess counterweight material) and bore the Mazda unit to the same diameter as you cut the center out of the VW one. The bit that is critical is to measure the depth of the clutch surface, remembering to add you adapter thickness, to locate the distance from the VW crank flange to the Mazda clutch surface. Do this BEFORE cutting anything up, since the two may not match, and you may end up needing an intermediary piece to connect the two. Press everything together and weld the seams CAREFULLY (to keep things round, little opposing stitches to start with - then burn them together) and then you pretty much have to re-finish the flywheel and re-balance.
BTW: Could you ask BIGBLUE to share the CAD drawing? It may be the most valuable bit of VW tech stuff in the world of swapping (engine, not wife).