Dodge Dart Sport

Thats a good price for the condition of the car. I have well over 9k invested in my 73 340 dart sport and that was just purchase price and cost to go through and get it mechanically sound. Still need to buy a couple grand worth of body panels and restore the body.
The good news is the aftermarket is stepping up for the 73+ owners. I see classic industries is getting ready to repop the grills, headlight bezels, park lights(TS) and trim. Tail light lens and bezels are available now. Im seeing a lot of 73+ cars for sale lately. I guess the supply of all the early ones are starting to dry up. I dont care for the beak front on the dodges but it does grow on you after a while. In my opinion, they got it right with the 72.
Buy that car and drive it for a while. I think you will find it has more than enough power without adding boost. Also, rear disc brakes wont help you much. Yeah they will help but for the $$ it cost you might want to invest in other parts of the car. The factory front discs do a decent job of stopping the car. It requires more effort than the new cars but it stops just fine.
Good luck and im sure you will enjoy that car for many years.