Electric Tach question

[TeriAnn Wakeman <twakeman@cruzers.com>]

I currently have a car with a four cylinder engine.  I have a neg. earth 
MGB tach counting the revs.

The engine will very soon be replaced by an 8 cylinder engine ("Dr. X 
will build a creature").  I'm assuming that the MGB tach would read twice 
the actual RPMs.  How hard would it be for a gauge shop to convert the 4 
cyl tach to an 8 cyl tach?

Alternativly.  Where might I source a Smiths/Jager 8 cyl tack that is the 
same size and looks similar to the MGB tach?

Dr X
(No this will NOT be going into a TR3)

twakeman@cruzers.com