as has been said...all is in kata
Several excellent sources have been cited and I won't take up space repeating those.
In doing the Pinan/Heian series you must take into consideration which version you are doing. Funakoshi too the angles out of the forms for introduction into the Japanese school system, to make it easier for children. Those versions are what Shotokan uses to this day, in most cases. The Okninawan versions retain the angles and that is what is needed for effective in-fighting, in my opinion, for the distancing problems.
That being said, anytime you turn more than 180 degrees consider that you are doing a throw of some type. Would you really turn all the way around to the left to face an attacker coming from the right? I think not. Also not many techniques come in threes. Would you consider moving straight ahead into an attacker with three steps, executing three upward blocks, as in the first half of pinan 2/heian 1, or three punches as in the second half? Probably not. Perhaps the first motion is a stun, the second, an initial grab, the third, a second grab and off balance leading into a throw, as suggested by the next movement, turning past 180 degrees.
Another source of bunkai is the books by George Dillman. I may not agree with a lot of what he says, and think his books are overpriced, and several other things....but the information is interesting and may help you with what you are looking for.
With respect,
Mitch Saret