AFAIK the machining of the block to suit a silver top/CVH pump is for a ZVH conversion (or silvertop head) as the blacktop cambelt goes straight over the block waterway. This was always a problem/issue with the WRC engines.

Although a reversed impeller will work (PF said they were getting one from USA for Project Peanuts) I wouldn't think it was too efficient as the pump housing is cast to suit the designed rotation.

PF did say (for Project Peanuts) that Retro-Ford had a solution, presumably for RWD primarily.

The other option which will work, is to just remove the impeller fins and use an electric pump.