396 Casting #'s but really a 427 ???

[isa70shovel]

Below is what I had posted on another site a couple of hours ago. A guy had answered with some helpful information but said that I would probably get better answers here. With the crank that I have in it everything spins freely.

I was on here the other night askiing for help but with the ID of my BBC. After a little more research I am even more confused. I have a BBC Casting # 3855962 which all that I can find and hear is that it is a 396 from either a Z16 chevelle, 65 Vette(425 HP), 375 HP 66 Chevelle, or a 66 360 HP 4 bolt main. I want to believe this but measurements tell a different story. I measured the top of the bore and the piston skirt with my Calipers and they are both 4.30+. I put a pick of the crank with this and it looks like the # is 7416 (the 7 looks like it was partially knocked off). Which is a 454 Crank. Looking down in the crank case I can't see anywhere where someone cut for clearancing. While I was looking in there I saw casting #'s and it freaked me out a little because the engine doesn't have any #'s on the front ID tag where they are supposed to be. The casting is right behind where the timing chain would be near the cam on the inside of the motor. The cast says Pass961, Hi Per962, B12. The last 3 of my cast is 962 so that # makes sense but the 961 throws me. The 961 cast # is used for 396's and a 66 vettes with a 427. The cast on the side of the block looks like it says I 28 5. That should be Aug of 65. Look at the pics and tell me if this makes any sense to anyone.

[pdq67]

No stuff on the deck pad, it's a crap shoot!

Imho, I 28 5 probably make's it a 1975 454 P/U or maybe a big car engine only b/c I forget when GM stopped installing the 454 in the 'Vette's. (Still a great core engine to start with by me and my 496 is made out of a "TSC" 454 P/U engine block)...

pdq67

PS., I don't think an early 396 will bore to 4.31" over, but some will bore to 4.25" if sonic checked.