looks awesome Dave ,..you did a great job on her,.
something that you can use concerning centering your compass,.. is a product called magshield,.it's relatively inexpensive ,..there are a few places that carry it,..some computer repair places ..etc..you can wrap your down tubes or any tubes that might interfer with your compass,..with this material ..it is very light,.. it will block any magnetic signals,..
I use it on my magnetic motor I designed, on the beginning of a rotational cycle when the magnet's are apposing each other,.to block the magnetic fields..it will allow you to take 2 magnets ..with like poles facing each other ..normally repelling each other ..place this mag shield between them ,,and it bends the magnetic field so both magnets get attracted towards the magshield,..once passed the edge of the magshield they repel again creating rotation.. this will ,..I'm sure also block a any metallic object with in the compass's magnetic field,.. therefore making it's presence null

one place to get it is
http://www.magshield.com.au/

there are also places with in the states to get it,..
just a thought

Chase