A833 NP A body trans ID help & intro.

OK, I do not have a 4 speed OD box, It's a normal box and am curious around what year it is. There is so much more info available now, then my last project 20 years ago. In my day, most 4 speed trans had numbers stamped on the id pad. Nothing on mine. Guy I got it from didn't know its origin unfortunately.
Rob, of course I'll sonic check. Core shift has alot to due with this also, and all blocks are not created equal. This is not my first rodeo.
My last 360 build, the machine shop checked the cyl. walls and told me .120 was not a problem, as he had done many 1971-72 at .100 to .120. I ran mine pretty hard and never had any problems. I believe RustyRatRod here said the same. If I do a 408 I'll just clean it up, as the cylinder side loading is greater with a stroker. At 71 I'm just here to have fun and learn what I've missed out on for 20 years.
Boy did I get lucky! The guy I got my trans from chased down the original owner. It came out of a 1968 Dodge Dart GTS-340. So, any guys around here that can give me info on why the id pad is unmarked???
Thanks for the 318 info, but it's getting pulled and preserved. It's the original and only 54,000 miles. 360 is going in its place with the 4 speed box. I'll check out Rob's build for sure.