need help on build 440

Q1) 71 440 will be fine
Q2) Not all 67 heads are closed camber. 452 heads came with both close and open chamber. With the hp I think you are looking for, just about any head cleaned up will work.
Q3) If you plan on turning alot of rpm or have alot of mix matched parts.(not all parts from same engine)
Q4) Yes they are heavy, but will work just fine depending the rpm range you are wanting to work in. The motor won't rev as fast or as high as a lighter balanced assy.

Go to Moparts.com and on their tech page I think you will find most of your answers.