There are no VIN numbers stamped on a 67 engine. It can be date code correct, and that's it. It's expensive enough already to build a 273 and adding a stroker crank to the equation will only make it worse. I just built a 273 for my 65 Barracuda. Custom forged flat top pistons from Race Tech, for stock stroke 3.31 crank cost $700. Rings cost $200. Race Tech already had a CNC program for the pistons, so they were cheaper because they did. Pistons for a 3.58 or 4.00 crank will be more, and a 3.58 or 4.00 Scat crank with 273/318/340 mains will be probably $1200 plus shipping. Then you get either a 302 or 335 CI motor depending on which crank you choose. I fully support building your motor however you choose and look forward to watching the build thread if you make one, but knowing what I know from recently going down the 273 Rabbit hole...I personally would never build a stroker motor out of one when I could spend less money doing the same thing to a 340 or 360.