400's are they any good?

I have the chance to get a 400 BB and a matching 727 transmission from a 70' s chrysler newport for free from a guys parts car, only thing I have to do is get his car he is fixing up running for him and he will give it to me. Are these 400's any good or are they boat anchors? are they a B block or RB? I'm looking to put it into a 77 dodge 1/2 ton. sorry for all the questions I'm more familuar with the 440's and 383's