You will have a lot of fun with the f.a.s.t. class ..
I am no expert yet , but I am plagued by a lot of weight on my car a 71 GTX fast car ..
Take advantage of litening up the car now , the heater box is Mint , but it adds weight. I see the six way seat . etc. Id be thinking about ANY way to liten up the front of the car .. If you want to Run real fast.. , if you just want to run respectable times and have fun , leave it "as IS"- But IF you get the "bug" youll eventually be pulling all that pretty stuff out . It Is a HEVVY car
Im assuming youll stroke the pee out of the 340 and beat up some big blocks with it.
Did that car come from NC , looks like I looked at that one before .
Good Luck , look forward to seeing your progress on it .