I really should do more research before posting...  Can I use an
inductive pickup (like a timing light uses) to clip onto a plug wire
and then somehow read the results with a multimeter?

~jp

to answer your question about the tachs at pep boys it would be hard
to use as testing only to just hook up and not mount permanently im
not shure about dwell tachs but some of the multi meters come with
inductive pick up leads for this purpose i have a blue point meter but
they can be costly but check into multi meters you may be able to find
one not so costly plus then you could use it for many more testing
purposes good luck