I did not go with the crate motor, but I did go with the Ford Racing 342 Short Block. Same as a 347 only standard bore, not .030 over. I used the Edelbrock Performer RPM package (heads 2.02/1.90, cam, intake, 600cfm carb, and waterpump). I dropped this into my Backdraft with a T-5 HD tranny and the BMW 3.47 IRS. I took it to the dyno and pulled 332 RWHP and 341 RWTQ. I was quite impressed, it was about 30 HP more than desktop dyno said it would have. As for streetable, it is great. As for sound, it is also great. Not the same as a big block, but still sounds sweet. The heads I have produce 10.5:1 compression, the cam is just on the edge of lumpy at idle, both of which contribute to a good sound. I do have to check to
oil more often than a 302 though. Even though Ford used pistons that don't let the rings interfere with the piston pin, it is still a long stroke for a 302 block, and does burn a little
oil. If Ford made a 327 or 331 short block, I would do either of those first. I think they might have a 331 crate motor. All in all, it is a great motor for a Cobra.
Good luck with your quest.