newbie transmission question

Well, at a glance, the first thing to figure out is whether you're looking at a 727 or 904 transmission. There are two easy ways to tell: First, the 727 is a big mamma jamma, and the 904 is more reasonably sized. Second, the trans pan on the 904 looks like this: and the 727's looks like this.

The 727 is most likely to be a v8 trans, but there are slant six 727's out there.

The next thing to decipher, is whether it's a v8 or \6 trans, the quickest way to tell is to look at the starter location. On a v8 trans, the pocket for the starter sits at about 4 o'clock on the trans, looking at the front of the trans. while a slant six trans will have it closer to two o'clock. see: V8 and \6

If the transmission is a 727, it may in fact be a big block transmission, I'm not familiar with the difference between the big and smallblock trannies, But I believe the starter location is different somehow too.