Silca stated they don't make these anymore and I can't seem to find them anywhere.

Anyways, I was looking through my scrap and found a poly rod that roughly matched the ID of the pump body.

After some cutting and some time on the drill press, I ended up with this:

Untitled by tk_1971, on Flickr

In order to make the stop on the top of the cap, I figure I'd melt the top and mushroom it on my counter top. I tried using my stove:

Untitled by tk_1971, on Flickr

It was going way too slow. I then pulled out my MAP torch and made quick work of it:

Untitled by tk_1971, on Flickr

The trick is to apply even pressure when mushrooming the top of the cap:

Untitled by tk_1971, on Flickr

Re-drilled the 10.3mm hole (13/32") on the top cap (because of all the mushrooming), measure, and cut to size:

Untitled by tk_1971, on Flickr

Untitled by tk_1971, on Flickr

Put the cap in place, drill the side holes, and finished!!!

Untitled by tk_1971, on Flickr

I put a small dimple on the top to indicate where the hole is at for future maintenance use (for alignment).