Hi not to sure what you mean by pennys.
I have a 50 ton Hydraulic press but it wont move in thousands of a inch no of them will, what will happen is you put pressure on then bang it will move say 2 mm.
What you need to do is LOAD it up say to 2000psi than hit the flywheel web with a copper hammer and you will se the pressure gauge drop. Are you trying to press it apart?
Have a look at this photo this is how I push mine apart put a 10mm thick plate (with a vee cut out) between the Flywheels and use a Wrist pin to push on the crank pin.
Load it up and hit Where my thumb is hit that part with a copper mallet and it will shock it apart just a few tho.
Now checking for true, You can put it in the lathe between centres but if the ends are bent then you will not get a inaccurate reading. What you need is one of these.
As you can see it runs on the bearing tracks, if you Don?t have the use of such a jig you can fit the main bearings on to the crank and place the crank with the bearings on V-blocks (let the bearings in the V-block) and the clock up both ends.
Hope this all makes sense