The original PUP is air cooled, and has a rather poor valve rocker geometry. I modified it a lot. I made my own patterns, but had them poured by a friend that runs a small commercial foundry.
The block is cast with a core and has cast iron sleeves pressed in. The head is made in two pieces and milled out for water passages. I have made all parts- camshaft, piston rings, spark plugs,etc.
I finally got it to run on Sunday August 13, 1995. I had a few water leaks in the jacket and cylinder head, but those are fixed, and it has run. Now I need to make a proper display stand, a radiator, and otherwise tidy it up.
I have run it the NAMES shows and Cabin Fever Shows several times.
If you really want to read all about it, Ive written a long article, with 7 color photos, Waterpup.