The fact that IM is no longer producing internal combustion-engined replicas - has to increase the value of one of the original replicas. Henry (according to the book) was only about 15-16 then and was helping his dad build them - so it could be a nostalgic meeting with him. At one point Frank hurt his leg and was sidelined for a month - overseeing Henry's work in a shop that only held 2 cars at a time. The book said Henry was hoping his dad would move on to building dune buggies.
It also talks about some imperfections that transferred from the original well beat Speedster plug to the early cars. No specifics though.