Decoding engine numbers-know a pro at this?

The engine numbers on my Chevelle, they are a bit unusual. It has a big block, not original, and I'm not certain if it's a 402 or 396. The numbers stamped in front have been over-striked. It was done carefully, with three different larger sized fonts so that the original numbers are still clearly visible. The rear casting numbers are good and clear too. Had no luck using online decoding sites to get a definite match. I'm told that GM sometimes did this. I tried to get a digital photo, but the alternator is in the way for a clear shot.
If you are a whiz at engine numbers or know someone who is, send me a message and I can send you an e-mail with a hand drawn sketch of the numbers and layout of the overstrikes in proportion.
Thanks, Tom B.

Here are the numbers I have:
Front of block behind alternator - VT03Q5CLB
Carefully stamped over the Q is another letter "Q" in a larger font.
The leading "V" is a larger font than the others.
Carefully stamped over the "0" is a "4" in a big font.
Then carefully stamped over this "4" is a "6" in a very huge font. I say carefully because all these bigger sizes are centered in a way so as the originals are still visible.
It would appear that after all these overstrikes the final number is now VT63Q5CLB?
Then beside all this to the right is what is probably a VIN: 11D151198. These VIN numbers are clear and even and all the same size.
Now on the rear of the block drivers side it reads: GM 8 T 3969854 F.

I can get the cylinder head numbers too if needed. I think they are located under the valve cover? The engine is installed and running good so I'll pull the valve cover off at the next oil change if those numbers will help. I can do it sooner if it's essential to know.

I'm interested in what this engine is - 396 or 402, what year and what model it came from. Anything else about it would be cool too such as is it a 2 or 4 bolt main, HP rating, etc.
I can e-mail a clear digital photo sketch of how these block numbers look. Just ask. Thanks for your help!
Tom B. --- [email protected]

http://www.mortec.com/bbc.htm

A 1969 block is a 396. A 1970. 71, or 72 block is a 402.

http://www.nastyz28.com/decode.html

6th digit: Last digit of model year:
7 = 1967, 8 = 1968, 9 = 1969, 0 = 1970, 1 = 1971

Your block is a 71 so you have a 402.

It's not a Chevelle engine but my book shows 3969854 to be a 69 -72 396 with a 4.094 bore AND 9.8 deck HT.

The 402 engines started mid year in 69 Chevelles but GM didn't advertise as such until much later.

By the way, the way to tell a true 396 from a 402 is the 396's had a two character engine suffix code and the 402's had a three character code.

Go to Team Chevelle - http://www.chevelles.com forums and go to the "Tag Team" forum, there are some people there that are very happy to help out with decoding.

Thanks for the information both of you. Now, I couldn't find the 'tag team' forum on the website......do I have to become a member first?
Tom B.