Hop to this one backwards... Mystery Cache

The cache is not at the posted coordinates, the only thing there is an abandoned well. Don't fall in the well, instead you must solve the puzzle below to find the real location of the cache.

A few letters have more than one value.

I came across some information the other day while trying to solve a puzzle. A little light bulb went off…this would make a great puzzle! Sometimes I’m Pinky and sometimes I’m the Brain. This was one of my Brain moments. As with most puzzles, you will have to do some math.

And now for the puzzle…..

Ir is 14, n has no value but is important

OaBgPl BkSKBBpAl IbMa

WiBa IpIr SaAa PaPaPa

Irn

You can validate your puzzle solution with certitude.