Time to get started!

So i just got my hands on a 71 Dodge dart "swinger special". I got it for free from my GF's friend, she was only the second owner, and that girls grandmother was the first, and it only has 175k miles on it. It hasnt been run in 4 years, but they said it ran great until they just stopped driving it. He said it needs a new radiator (husband saw it leak, im gonna check the hoses first, but that should be easy) and a new master cylinder (which i also dont think would be too hard. When i used the Vin Decoder it said i had a 225? i know its the slant 6 engine, but can someone tell me if its a 3.2 L or a 3.7L? also would one of THESE be the right one? I want to do alot of work on my own, but dont have that much experience, which is why i came here!

If someone knows of any how-to's on both the radiator and the brake work, that would be awesome. Thanx for all your help, im sure ill be back with plenty of questions

OH ya, also he said the gas gauge stays on full until its empty, then it drops... can anyone point me in the right direction to fixing that? and what is the aproximate MPG for this car? hopefully it wont be to long till i get her running, thanks!