James, welcome to VAF.
A letter to Vans, with a copy of the bill of sale, and a copy of the prior builder number paperwork should be all you need.
At least that is what it took when I bought someone else's project, but then there was no international factor to it.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."