The only real troublespot when installing a Miata gearbox in an MG is the shifter position. The shifter ends up positioned about 3 inches further back and we have to modify the tunnel to compensate. When we do this, the stock cover no longer fits. In the case of this 1967, it still had its original steel cover which needed to be modified to fit.
We cut it apart at the most logical spots for patching and welding, and then fit it to the car in 2 pieces. Once we knew what we had to fill we fabricated patch panels and welded them in place. After grinding, the modification looks like a stock piece, only longer. Once the driveline in our project has been removed we can get under the tunnel to install weldnuts in the proper position to bolt the cover down.
We also test-fit it to our center radio speaker console (which will be housing a pair of HVAC vents, the HVAC controls and the seat heater controls) to make sure everything was in its proper place. This console normally holds a single mono radio speaker, but we've mocked up all of the changes to this one before machining the final pieces.