I recently purchased a good track crank (Avocet) which specs have been hard to find. I had hopes of installing this on my Breezer Lightning but the cranks fail to clear the chainstays. I have not dis-assembled the current Race Face triple but a review of it's website suggest use of a 113mm spindle. How would I determine what size BB/spindle to get if I wished to make this configuration work? On the flip side, how would I select a single speed crank to fit the current BB on my mountain bike? Any constructive assistance is appreciated. Thanks ...Barley

Man. These things are in the realm of the most difficult to figure out. The very expensive Phil Wood hubs have 5mm of lateral adjustability to overcome some difficult problems.
If you measure your current spindle length (accurate to the millimetre ) go and buy some washers that fit over your spindles and measure how much extra space is required on the crank side when hand aligning exactly how much farther out the cranks would have to be for both the chainring and the cranks to clear the stays, then you could buy a spindle that is twice the difference required longer than your current spindle.
If you cannot figure out what the h*ll I am saying, you need to take it to someone who can swap out parts for you.