No idea where you'd mount it.

Had one in my RRC-with-Peugeot-2.3 Turbo diesel conversion.  It was
controlled by a time switch and absolutely wonderful (the Hotstart, not
the conversion).  I also fitted a temp switch that turned the heater fan
on (and the radio! - shared supply, apparently) at a suitable temp.
Result - toasty motor that started without a puff of smoke and had a hot
interior.  No idea if it improved fuel consumption - I didn't care -
warmth was what I was after.

Kenlowe were very good as well when it kept blowing pump windings. They
replaced it 3 times IIRC.  Eventually I discovered that it was my time
switch that was at fault.  For some strange reason the hotstart did not
like the mains being switched by a TRIAC and I changed to a very large
relay. But that's all irrelevant.

IIRC the mounting is seemingly unimportant apart from the orientation of
the pump axle - or something similar, i.e. there is only one critical
plane of orientation.  It must be plumbed into the heater side of the
thermostat, not the radiator side, and you must have the heater valve
open, i.e. set to hot, so that the hotstart pump is able to circulate
the heated coolant through the block.  You can extend the hoses as far
as you, reasonably, like.

It's funny, I had completely forgotten about the Hotstart.  I'm
seriously think of replacing my current (V8) RRC with a diesel Isuzu
Trooper - a Hotstart would be ideal for that.

HTH

Richard