M40 1.8 to M20B25 Conversion Question

[furbster]

Hi Guys,

I've got an M20B25 for sale complete with all ancillaries, loom, radiator and box and have been asked by a zoner what's needed to convert from their M40 1.8.

Is it a fairly straight forward swap? What else would they need?

I've been trawling through the forums and can only find info on M42 to M20.

Thanks in advance