The most definitive list of known block applications is provided by Colvin, and this is what CRG uses as a baseline - Colvin researched back to original Chevrolet factory data - all other lists are frankly suspect. CRG takes some of Colvin's work a step further for 67-69 Camaro. In the CRG link header at the top of the forum pages select the 19xx Model ID and scroll down to find the info to ID your model (at least most of the V8 models).
The particular block you mention, 3858174, is primarily known as a 66 block and isn't known to have been applied to 1967 models, but I can't rule out a 67 application. That the block supposedly has a large journal crank with a Dec 66 date indicates that - if crank is original to the block - that this block would have been in a SS350. However, my statement above stands. You should still see a 67 Camaro partial VIN on the block stamp along with one of the 67 350 motor codes shown in the CRG link above. And CRG has yet to see one of these blocks in a documented original Camaro.