It appears that what you have there is an old school style FE build that in and of itself is a pretty neat piece that has absolutely nothing to do with a Shelby Cobra, either the specific one you mention or any other. For one thing, I have never seen a Cobra with a blower on it. As others have mentioned, for you to have any shot at credibility when selling this still decent engine, you need to drop any and all references to a Cobra. This is almost certainly not a Cobra engine.
That said, there are some nice components there. Looks like a Milodon road racing style
oil pan. Hard to tell from the photos but it looks like a very nice valve train setup on there. The Dove Canadian type heads are old school and surpassed by the more modern heads available from BBM and others, but they're decent pieces nonetheless. Edelbrock water pump is good. That blower intake manifiold is becoming a holy grail. They're very hard to come by and for someone who really wants one they'll pay a lot if cash for it. Other than perhaps the blcok, that intake might be the most valuable piece on this engine. A sideoiler block always has value. If it's a service block, it's at the lower end of the sideloiler block value scale. If it has more than one or two sleeves in it, the value starts dropping sharply. As to "strengthening the ribs", you've likely been sold a bill of goods on that one. If it's a boat engine and has seen salt water, it's value drops off a cliff. You'd need to give more info on the cam setup, valvetrain, and the rotating assembly, as well as a block casting number and the exact number of sleeves it has to get a decently accurate value number from the crew on here. That said this most certainly ain't a Cobra engine. It is a pretty cool piece though. Good luck with your sale.