Looks like a nice car
Trim# 815 = Black SS Convertible (bucket seat)
Paint#948 = Honduras Maroon
You are correct, 340 HP is 63-4, 380 HP in 1962
Here is a link on other identifying characteristics of a 409 from the 348-409 site.
http://www.348-409.com/348409identify.html
The most obvious is the fuel line, is it routed outside or inside of the passenger upper control arm pivot?
Verne - correct me if I am wrong here on anything.
Jake