[Moritz55]

I'll share my experience this past April here in NC on registering/titling mine which may be similar to what you will be going through in FL.

So... in NC since an SPO or BD are a Replica (Kit) Cobra their VIN number (SPO2454 example) is NOT allowed on the title. Because they are Kit cars, they are NOT NHSTA (National Highway Safety Transportation Admin) approved, this means a Unique VIN number from the state is supplied. (I have a unique NC VIN now... not the SPO VIN number)
.... I think in CT the original VIN was for this reason... so it will be impossible to change this VIN unless FL does not require NHSTA approval for a BD kit car?

In NC, they did not care at all about the Year (1965) on my Title when I registered it. I did have the documentation and original title that did say 1965 so not much work here to keep it titled for that year.
.... the only advantage I can see of having it titled as a 1965 would be that annually it will NOT require an inspection when renewing the registration. Maybe check this in FL?

It was a pain for me registering in NC because no-one really knew how to do it for a Cobra ..

Good luck...