I have a 302 in my z28 with 202 angle plug heads on it . I had it rebuilt the plugs I had in it were TRL79 champions but the book calls for TR79 on the stock 302, they are half an inch shorter , which should I use ???

To be quite frank with ya I do not know as much as I should about the 302 engine. Did the heads you before mentioned come on the engine? If they are not aftermarket what you would want to do is go by the engine they came off of as to what plug to use. If you have the heads off the engine, screw the plug in and check where it bottoms out, if is is flush, you are in luck. If not, try other plugs. Your local auto parts store should be able to help you out.

Which head do you have?

I would use whichever plugs are designed for the heads. Your heads may place the spark plug in a different depth than the original ones. If the plugs are too long, bad things could happen.

I don't think any engines had stock angle plug heads on them from the factory, did they guy's? pdq67