Does anyone have the compression numbers / spec for the above noted motor? I know that the early ones were around 8.5/1 where the lator ones were closer to 9.5/1.
The Haynes manual from a fiero for the Duke said:
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No cylinder should be less than 100psi
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The difference between the highest and the lowest cylinders should not be greater than 30%.
So what are the actual compression numbers for these motors? I am betting it is around 145-155 but I can not find it in writing.
I was testing a Postal truck and got some astounding numbers for a vehical that was 18 years old and only had 20K miles (astonishingly bad numbers!)
BTW after playing with one of these postal trucks I WANT ONE!! It would make the coolest work/junkyard/hauling stuff 2009 challenger vehicle ever!!! Think mid mount V8!!! Makes going postal a good thing. 
Ohya and then there is the whole right hand drive thing 
I am not personaly very farmilliar with the iron duke, but the compression figures in your manual sound realy low to me. 100 psi is flat head lawn mower teritory. Your guess for the readings sound reasonable ,if not a bit low, to me.
When I take compression readings on industrial engines I use an auto parts store compression test kit (cheap simple and reliable). I hold the throtle wide open, and when possible take all the spark plugs out so the starter can spin as fast as possible. I keep cranking the starter untill the gauge needle peaks.
Using this method I usualy find healthy ohv engines with compression ratings betwen 8.0:1 & 9:5:1 read between 150 psi and 185 psi. Flat heads usualy come in at 120 to 150 psi. (and there are still plenty of flat heads in use in industrial applications). Interestingly, I have found that most auto engines with high compression ratings don't test much higer than the modest compression industrial engines. I have tested at least one motorcycle engine that hit 200 psi.
BTW I love your idea of postal truck challenge car, but why not just put that V8 into your fiero?
