Jet drive identification and rating

Hi,
I am removing a jet drive unit from a 12'6" jetboat. I don't know what engine it had before as it is a bare hull but suspect it was a car engine as there is a step up drive (1:1.5) to increase the revs from the engine to the pump shaft.
Before I spend time cleaning the unit up, I'm trying to deduce if this jet unit would be suitable for coupling up to a 120hp motorcycle engine in a similar hull.

The jet drive is a 2 stage unit with a glassfibre, moulded into the hull pickup tube and aluminium parts outside the hull.
It has 150mm impellers (x2) and tube.The impellers are bronze.

It has a makers plate on the reverse bucket which says:

JET UNIT:
MODEL NO 64
SERIAL NO 1117
UA ENG. LTD SHEFFIELD.

Am I wasting my time with this old 2 stage jet? I note jet units now tend to be single stage.

Second question:
It needs cleaning up. How do I restore the old pitted oxidised aluminium to better condition, are there special paints and primers i should use?