i bought a 68 that has late model 350 motor it has a large 3 groove pulley on bottom that they had to nocth releif in subframe to fit i would like to get back to correct pulley size but not sure what is involved to fix ?i have 11bolt water pump that is 4 1/2 so if i buy the corrct pulleys what elese changes?i assume i need 4" water pump and all the 68 brackets please advise