850 Spider water pump compatability question

[Rafiyank]

Hi everyone and thanks for any assistance...
I own a 1967 Fiat 850 spider. The engine was replaced by a previous owner to a 100GBC engine (903cc with 4 bolts water pump). The pump needs replacement but it is hard to find new ones and they are very expensive.
Found a water pump that was fitted on the Seat 133 903cc engine. The pump looks exactly the same, but I was told that the mounting angle is a bit different and that it will fit later models of the 903ccc engine (a112).
Did anyone tried such a swap and can share what modifications are required?
Thanks!