Hey Spud,
You may or may not be interested and I know artists have their preferred materials that they like to work with.But if you are I could put my old horseshoes aside instead of chucking them out.Send them up either with someone else or if I can make it to the birthday ride.
The amount of times I am asked for old horseshoes is to many to count.Even the Farrier from the site makes these ornamental sculptures for gardens out of them.
I reckon a motorbike and rider made out of horseshoes has a pretty cool irony to it,old vs new.
As for the quote, You only go round once. 
Cheers James