The 3.0l is timed, the 2.7l is 'phased' - that is, the pump needs to be 'on stroke' when the LH camshaft it's driven from has the least load on it. It was never documented (which is probably why some people say it doesn't matter) but it was a well known cause of poor idle and acceleration within LR dealer workshops. In truth, the camshaft and pump would rarely be moved during rear belt change, some indies seemed to want to move the pump pulley, or maybe it moved during belt removal if they didn't cut it? We never had any issues with dealer-fit belts, occasionally indies or DIY though.
Any vacuum gauge will do it, just remember you need to allow air in to measure the vacuum, if there are restrictor plates, start with the largest hole and work down until you get a meaningful measurement.
Any vacuum gauge will do it, just remember you need to allow air in to measure the vacuum, if there are restrictor plates, start with the largest hole and work down until you get a meaningful measurement.