Here is a link to an image of the remote for the 308. It would seem that MF made one remote for the 308 amp, cd player, & tuner.
If you look at the next image there is a picture of a Logitech remote (Harmony 200), which was a popular learning universal remote at the time. You would enter the appropriate code and the remote would learn the codes. If this is the case, you may have better luck tracking down the Logitech,
http://www.usaudiomart.com/details/649097437-musical_fidelity_a308_integrated_amp_made_in_england/images/670444/
Rich
If you look at the next image there is a picture of a Logitech remote (Harmony 200), which was a popular learning universal remote at the time. You would enter the appropriate code and the remote would learn the codes. If this is the case, you may have better luck tracking down the Logitech,
http://www.usaudiomart.com/details/649097437-musical_fidelity_a308_integrated_amp_made_in_england/images/670444/
Rich