as long as the bios on his chip that's going in your machine is compatible with your xbox version is does not really matter.
example:
if he has a version 1.0 - 1.5 and so do you, you will be fine.
if he has a version 1.6 and you has a version 1.0 to 1.5 you will need to put a 1.0 - 1.5 compatible bios on his spare bank so it will boot in your machine.
All you need for the hotswap is a bios that will boot in your machine. As long as you can use his chip to boot you will be fine.