Each engine I build is tested before it leaves the assembly stand. I check compression and oil pressure using a section of bell housing and a starter motor. The engine is spun with no spark plugs and the compression is consistently right around 140  150 psi for both the 1.9 and the 2.1 engines. Yes they have different compression ratios but they also have different camshafts and that affects the reading as well. The oil pressure when cranking is is 50 to 60 pounds and the bounce of the gauge I observe is the pressure relief plunger bleeding off pressure. If your numbers are low and you feel its not the gauge then I would conclude that the valves have been preloaded when you assembled the engine. The preloading would also account for some of the poor idle. I would not expect the cranking compression reading to increase over time. You should see the oil consumption and crank case pressure will drop when the rings seat. 

Bob Donalds 
http://www.bostonengine.com
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Philip wrote

> Ok, I got it to run and set timing to the "v" mark.  Have put about 30
> miles on it but it still runs a bit ruff.  Was curious and did a
> compression check, all cylinders between 100 and 120.  That seems a bit
> low.
>
> Questions:
>
> Can I expect compression to increase over time?  I hope so, and perhaps
> and just a bit paranoid
>