ok for an inexpensive 408 motor, get the block, but try and pay less than $150 for it, $100 would be better. find a stock 400 ford crank, and have the counter weights, and the oil slinger at the rear of the crank machined to fit the 351w block, and the pistons you will be using. you can also get a set of stock 351w rods, when a little prep work is done to them, they will handle the power you plan on throwing at them, and get a set of 350 chevy pistons. have the small end of the 351w rod honed out to the chevy pin diameter so you can keep the press fit, rather than floating the pins. if the block needs to be overbored, then do it, but go as small as possible, .020 would be nice, .030 is standard. you will need to notch the bottoms of the cylinders for rod bolt clearance. regarding rod bolts, use the arp wave loc rod bolts as they are very strong. to prep the rods, after having the rebuilt unless you get new ones, have the seams smoothed down, the rods polished and then shot peened. dont forget to balance the rotating assembly. with some judicious shopping, and doing some of the work yourself, you can build the short block for about the same money as just getting the rotating assembly kit(for a 408 usually around $1500 for the cheapest one). if you dont want to use chevy pistons in your ford motor, you can get a 3.85 stroke cast crank, still use the 351w rods, and hang a set of ford 302 pistons on the rods, and get(.030 over) a 393ci windsor that will make the same power(only 15ci difference) for about the same money. you dont hav eto spend the big bucks for a complete short block, or a complete rotating assembly.