is my car in any way special/rare or more valuable than any other? 70 340.

As 68383GTS said there were 955 3 speed 340 Swingers built in 1970, so you have a rare one...however, once customized, rarity becomes a mute point for the most point. Poeple looking for a rare car would be turned off by the non stock additions. Like I said, if everyone built their cars the same way our hobby would be boring...and the aftermarket wouldn't exist. In my opinion, I would prefer to see a slant 6 car customized before a 340 car, but when your name is on the title, you call the shots.