The 350 2brl is a minus but the original condition and low miles is a huge plus. You have some rare options as well.
I would place most of the value on the condition and low miles so to appreciate from $30k in the future. You will need to maintain it as such i.e. not a "driver car".
The bottom line is if it is in good condition and you love it then it's worth it. Just do not let them know you love the car until after it's bought. Tell them it needs to be a 400/4 sp to get the kind of money they want in today's market. Offer them $25k and see what happens.
An appraiser would be helpful IF he/she knows a lot about FB's otherwise it's a waste of time. Use him for insurance only.
P.S. Love the colors!
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________