Not familiar with that block number but I can say the "291" head is for 1968 production. Last year of the true camel hump head.
block and heads cast in October 67, engine assembled Nov 14th 67 in Tonawonda, NY. The car was assembled in Wilmington, DE. Nice motor.
The vin derivative looked interesting to me...starting with 8Y.....so 8 in this case is 1968...never seen Y before in my life. Had to look it up...Y is Wilmington Delaware..they only made full size cars in 1968. I guess being in CA, it'd be unusual to see a Y code car out here. There were many plants between Delaware and California in case they needed more 1968 full size Chevys out here. Looked it up ..there were 9 plants in the US making full size Chevys in 1968. Amazing. 9 plants.
My Chevy II was built in Framingham MA, which is a long ways from Arizona, where I got it. Cars (and people) move around over the decades...and there were other reasons for GM and dealers to move cars around, before they were sold.
Yup, it happens...but exceptions don't make a rule. I've been into GM pretty hard-core for 40 years and don't recall ever having seen a Y code assembly plant built car in CA. I'm sure that the more east you go, the more common it gets. Chevy IIs were built in less plants so finding one far from its origin is more likely.