Are Mk1 and Mk2 waterpump the same ?

[RedMk2Gti]

As thread subject said.
I've got a NOS Mk1 waterpump just want to see if it'll fit Mk2, I'd imagine their block layout are similar.
The Mk2 is a little bit too hot.

[Golf Loon]

Late Mk1 has smaller bolthole spacing like a Mk2 for the pulley. Early Mk1 is different.

[sports racer]

Are you sure the pump is causing it to run hot? There are a million other things that can cause overheating.