I am looking at buying a 73 Mach 1 No engine or tranny included, originally had a 351 with a manual Trans. I currently have a 90 F-250 with a 460 and auto trans that I would like to put in the car. The owner of the car says it is a direct bolt in as these cars could come with a 429 but the last year I can with a 429 option is 71. All help greatly appreciated.