I think that the BSB LO frequency was 10770MHz so that will give you the frequencies that you need to feed to the STB. Don't forget the DC break to stop the LNB supply killing what ever you connect it to. You may be able to find an analogue 1.3GHz ham TV transmitter that covers the IF band if you are lucky. Unless you can find the modification info, I think that you are stuck with fixed frequencies. If you want a tuneable Ferguson box, modified for D2 MAC, I'm sure I had one somewhere
Edit: I measured a NoS BSB LNB and it's LO is 10760.9MHz so it may have started life at 10770
Edit 2: I found an X2402 EEPROM from that era which may have been loaded with D2MAC mod code for either a Ferguson or Philips box. OTOH, it could be blank or original firmware. If anyone wants it, PM me.