Whilst the Chieftain is a great ship and I like it a lot, I still have my FDL sat in the station as I like too. If your FDL gets shredded to pieces as I believe was said in your first post OP, I would hazard a guess, the Chieftain is not the ship you are looking for, and others have said, the internals are bigger on the Chieftain so the A rated cost of Chieftain and FDL is around about the same.
With how little I play this game with the extreme lack of any meaningful content, extreme need of 3rd party programs/sites to get anywhere or any info you need..
But...why play a game if this is how you feel about it?
I mean, yes if you had just enough money for a stock fdl (I personally don't fly anything stock but ymmv), you could get a mostly upgraded chieftain, but how does that change the "extreme lack of meaningful content"?