If you are trying to make it look and sound and perform closer to an original Cobra big block car, it's a great way to go and from a value standpoint. If you equip and build them right, they are fun to drive and wind up pretty good. There are a lot of Cobras around with 390s in them with 427 valvecovers on them, some just won't volunteer that information up front. In fact, I would prefer a 390 in a replica Cobra vs. a real 427 due to it's collector value for a non-replica car. Go for it, just make sure the cylinder walls still have some meat to them (sonic check) so you don't run into overheating problems due to an overbored block or due to core shift; and check every cylinder too. It might take a few blocks before you find a good one. Many others here on CC and Network54 can provide advice. FE's Rule! Hahahaha.
