another 383 build up Q

i am greatful for all of your advise! being this is my first mopar i am not shy about asking. i want this car to look great (which it already does) and be a real muscle car at the same time.

my dad found a dart (unsure of the year) for $450 and i am told its in better shape then mine. it is also in need of an engine/tranny. i am going to look at it this week and decide if i want it.

where could i find a 400 block? how much would i expect to pay?