Well, you will probably have to spread the shock towers appart for it to fit, it will be very tight like, pull the motor to replace the sparkplugs tight, unless you put a M-II front clip under it, this is with the 390 FE, i'm not shure about the lima 429 ( Fe's are 352, 390 and 428, the Lima's are the 429 and 460 ). if you want a basic bolt in, you could use the 429 or a 460, as long as you had a '69 or '70 Mustang as there were boss 429 mustang's made in 1969 and 1970, get all the front end/ suspension parts, mounts and everything from a resto catalog like NPD for a boss 429, and your lima 429 and, it would basicly bolt in. as for the 390 price, being 390's are getting widly used now, $100 for a locked up block would be an avrage, but, you may consider looking on, the crank is probably trash unless it's possibly turnable but, it's been exposed to the elements for a long time, the only value of the motor really is if the block is fixable and the heads.