Hello,
We can put a clamp-on flange on that pump so that it can rotate like you want. We machine off the cast-on flange and turn the right diameter on it for the clamp-on style deal (like the new pumps). We charge $179 for that and that includes the new flange. That includes reclearancing the pump and flow testing it. The guts must be removed to do the modification, so we include all that in the price. If it needs new bearings and a seal that would add as much as $55.
Rebuilding should be left to a pump shop...you could replace the o-ring and the seal yourself, but the bearings are a big deal and the clearance must be set precisely if it's going to live a long life. The pump's flow is directly affected by the end clearance. There's no way to change the bearings without pressing it all apart.
The DSR pumps (made by Enderle) are indeed just like a Chevy oil pump inside. However, the pump body is aluminum and they don't last like you'd think they would unless you keep it flushed out after every race. They do well under high pressure because the shaft that the gears ride on is supported on both ends (unlike the conventional design). But pressure isn't everything. Many of the DWR pumps we see here develop severe "cancer" inside...pitting in the aluminum body that degrades flow. You can buy Waterman pumps that are similar with a steel body, but they are very expensive.
On the conventional pumps, usually the only thing that wears is the lid (replaceable) or the bronze liner. The liner can be replaced, but it's spendy and not worth it most of the time. Because of the bronze, these type of pumps last years and years while being abused pretty hard. The vanes or "fingers" on the internals never fail on a pump that size. Not an issue.
Spud