I had the same questions as Steve. Thought it would have been a Yenko "410" car because the original 396/325 hp automatic cars were built that way. If they would have done the 427/425 hp short block, then they would have probably needed to upgrade the TH400 and/or at least the torque converter. I don't know of any cars this late that were originally 325 hp cars that were converted to 450. They may exist, but I have never heard on any.

It is the lower end or "tamer" version - but that is in NO WAY said with any disrespect. They still had more horsepower than an original L78. Any 67 Yenko is a rare find and you have a real gem there. Congrats!

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Wasnt dick harrell doing the conversions from the middle of 1967 into 1968?

I spoke to John the original owner this morning...he said during the conversion that Yenko went from the 396/325 camshaft to the 427/390 camshaft...that itself gave it .060 additional lift... then add the Doug headers....those 2 items by far surpasses the 410 HP . It helps to have the original owner to confirm info.
This car is an 06E build. And was the last 67 Camaro at the Yenko dealership .
John recalls Yenko ads offering the 427 Camaros. He went with his father in early March of 68 to purchase the car and waited 12 days for the conversion.

----Wow! Those interior pieces are perfect. This Yenko is going to be amazing when done......Bill S

What was converted that late? It was already a 427 conversion.

For the most part with all of the converted Yenko 67 cars....Don Yenko would not convert them until an order was agreed upon with a customer or network dealer or demo or if the car was sent directly to Harrell, Gibb Dana etc. Don was a Chevrolet dealer that advertised the 427 Camaro but was smart enough not to have several converted ( extra money) sitting on the lot . It was cheaper to wait for the guaranteed order. I know of other 06E cars treated in this manner .

Conversions were done under the Yenko agreement by other dealers...Gibb, Harrell, Dana etc. they were not converted only at Yenko and then shipped....that would have been to costly. Howard Sober was a shipping company used to transport cars from GM directly to dealers for conversion...especially Dick Harrell

Yep the 396/325 hp cam is tiny (.398 lift) compared to the 427/390 hp cam (.461 lift).

Ok, but seems silly to have a previous model year 396 car sit on the lot unsold for that long. I would at least have thought it had the 427 conversion done and then the other goodies added later. But your docs say it was all done at the same time so you are most likely correct.

What’s the casting date on the block? Assembly date (year and month) of the short block is also usually stamped down on the starter flange area.

I am going to send you a pm. I have a 67 L35 M40 car with a VIN less than 300 from this car. Sold new at Bob Eriksen Chevrolet in Milan, IL. No docs on it but I suspect it was converted, just not sure by who. It’s an 07A Tahoe Turquoise, Black Deluxe Interior, console car.