gm never made a junk big block engine the 366 is not a hot rod engine but there is many thing that can be used to build a396to 427. engine with the right short 396-454 short deck block . a 366 4 bolt main caps crank heads rods can be used to build some thing better if a tall deck 427 you can get 526 out of one and more $600 is not bad for a big block 454 if that is what you are getting . i do not pay that much for them i use just the blocks and build them to 486/496 or 513.but if you want just a mild build and you get a crank ,block, rods , heads, then your set