The date code is also stamped on the front of the block near the corner of the cylinder head and intake manifold near the distributor, above the fuel pump.

The first number will be the least significant digit of the year, the letter will be the month and the number will be the day of the month. For instance, my 289 has 3M1 stamped there. It was cast in 1963, December (the letters skip I and I think L) on the one is the first of the month.

The front stamping is easier to use since you don't have to get underneath.

Now, even that won't for sure determine whether it is a 289 or a 302 since the blocks are the same. In the late 67 model year they changed the 289 block a little for the upcoming 302, but used the block for a 289. I would think that anything with a stamping of about 7D or 7E would have started being used for a 302. Anything before that would probably have been a 289.

If it turns out to be a 7 year casting, you will have to pull the pan to know. On the front counterweight a 289, 260 or 221 crank (all the same) are stamped 1M. A 302 crank is stamped 2M and a 351W crank is stamped 3M.

Hope this helps,