You need to make sure that the mmc4 works on both channels - not sure that a beolit would accept the input from a beogram as it would need a pre-amp.
Sounds like a bargain though if it all works fine and the cartridge is good
Beovision Avant 32 RF, DVD1, Beovision 1, MX4002, Beound 3000, Beolab Penta MKII, Beovox Penta, Beolit 707, Beolink Passive, Beovox C30, Beocom 4, Beogram TX, 4 x Beo4, Form 1 & 2, Beocenter 7700, Beovox S65,