A bit late with reply as been very busy, Not sure If pump timing is critical as its just high pressure pump , but when I did my belt and water pump I had a few attempts to get the pump marks to line up , in the end I clamped the belt to cam pulleys with wooden clothes pegs removed the idler near pump so I could turn pump a tooth just past marker , and put idler back on, then when I set belt tension all lined up When I first stripped it all down I checked markings and pump was 1 tooth out but car ran fine I too struggled with water pump bolts but found it best to put the bolt in pipe bracket and pump first , line up and screw in part way before other 4 bolts TBH the whole job was a pig so many bolts difficult to get to