Cat VC60D Fuel pump issue

Hello All Recently I purchased a non running Cat VC60D. The original engine had spun a big end bearing. The seller had purchased another engine to replace it. The original engine was a Peugeot XD3P and the replacement engine is a Peugeot XD2. I found a few issues with the replacement engine that I worked through and fixed. One issue was the thread was broken off on the throttle lever shaft so I had to remove the top of the CAV DPA pump to replace the shaft. This throttle linkage is different to most DPA pumps in that there is no multiple settings for the spring and governor arm/plate. Eventually I had the engine reassembled and back in the forklift. When I went to connect up the fuel lines I found someone had installed an electric fuel pump and the original filter with a primer pump had been changed out for a normal filter unit. I found the outlet from the pump had been blocked up with an ants nest. I replaced the hose and purged the line but found the flow to be aerated so I removed the filter and refitted the fittings on the inlet and outlet and replaced the hose from the tank to the filter. When i tried to bleed the engine I could not get any fuel out of the bleed screw on the side of the injector pump. I checked the shut off solenoid and it was working fine. I then removed the inlet strainer and found two ants in the valve before the strainer however the strainer was clean. I damaged it getting it out so I replaced it with a new one. Reassembled and still nothing either at the injectors nor out of the bleed screw. I did some research and realized there is a priming valve in the end plate of the pump below the inlet. I removed it and found it to be stuck. I freed it up and reassembled it and I now had fuel at the bleed screw but still nothing at the injectors. I thought maybe I had misaligned the stopper shaft with the shut off bar and it was jamming the metering valve in the off position so I removed the top and checked but it was aligned. I also made sure the metering valve was moving freely and it is. I still cannot get any fuel at the injectors. I don't know whether to persevere with this pump or swap the one off the XD3P onto it. When I had the end plate off I checked the vanes in the low pressure transfer pump and they looked OK. Could there be a problem with the governor or could something be stuck in the high pressure pump? Most people that have issues with no fuel at the injectors appear to have found the metering valve stuck but that is not the case with mine.