cast iron water pump /on 5.2 magnum ?

OK thats a start.
Next question.. Can an Edelbrock 2176 Performer intake be made to fit onto a 1992 5.2 Magnum engine (the edelbrock magnum intake is to tall for my app.

Yes but the 2176 ports are quit a bit smaller than the magnum heads ports. (I am running a 2176 on my magnum right now)
Then there's the part where the bolt patterns are different.
LA (2176) intakes use a angled bolt orientation, and the magnum heads use a vertical intake bolt.
If you come up with a jig, or send your heads off to someone like Hughes Engines thay can drill the magnum heads for LA style intakes.
This is handy because it opens up a myriad of intakes we can use.

Then there's Engine Quest Magnum heads that can be ordered with the LA bolt pattern pre drilled and threaded. Engine Quest Part number CH318B

These heads are what I used on my 5.9 with an LA style intake.