I really would love to rebuild the 390 engine in my t-bird but after shopping around why is it so much cheaper to just by a rebuilt 390 already done from a good shop? I have gotten prices on total rebuilt 390's for about 1,300.00 all the way to 1,500.00. after crunching numbers on what i need to do to my original engine i am well above these estimates without a warranty that some of these shops include. is my thinking all wrong or should i get the rebuilt and save some big cash. i really would like to just use my engine and learn some more about the car but this doesn't all add up to me......why?