Hey 5Voltdude,
Looks like you may have a motor plate (purple) made for an F103 which will also have a different axle height, even with matching axle adjusters.
The F104 and the F103 motor mount sets have different heights so you will need to get a matching set of 104 peices.
That purple F103 motor mount is cool as hell and vintage if I'm not mistaken. I wanted one for a long time and did finally score one.
You can get the F104 set in plastic for just a few bucks. I'm sure TQ and Speedtech have that set.
Get the High Traction T plate, it's $15 bucks and fragile but is well worth it for asphalt and low traction. If you can stand it, get 2 cuz it'll break easily.