Re: need date correct 350 1968
I wouldn't get too hung up on finding a '68 350. There's only one engine that will substantially increase the value of the car, and that is the original one. I searched the orphans section at CRG for your VIN and nothing shows up. It'd be 100 times easier to find any pre-'87 350 and dress it up to look like it would've in your car. Other than that, you can pour through eBay and hope to stumble on a rebuildable one, check your local machine shops, or maybe someone on here has one they'd sell.
Experience...... It's what you get when you didn't get what you wanted.