Ignition Question - Part II

["Fereday, Chris" <chris.fereday@domain.elided>]

First I would like to thank Dave Biggs for taking the time to fax me the
instructions on installing a Lumenition system on a Stag (excellent
service!). It has resolved the issues I have been having relating to the
fitting of a new vacuum advance unit. 

I now have another related problem.
Can anyone explain why Leyland switched from a single point distributor to a
dual point distributor? Its my guess that it was to reduce the rate at which
the points burn out - is this correct? Also, am I right in assuming that
each set of points only deal with 4 cylinders each? I can't find any info to
corroborate this.
Dave's information shows that my Lumenition sensor is sited in the position
of the wrong set of points. If I move it to the location where the other
points would be sat, it would be correct, but presumably this will give me a
slight change in the ignition timing?

All answers would be appreciated on this matter. 
I did take the car to be tuned last Saturday (and have the sensor moved /
vacuum fitted), but it transpires that the distributor drive is badly worn.
I have sourced a second hand one as it appears new ones are no longer
available. The whole distributor is due to be rebuilt on Friday and the
afore-mentioned changes made, but I would like to go to the garage fully
armed with as much information as possible.

Thanks again
Chris
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