Were WLC heads and pistons standard WLA issue? Same compression ratio? Was a separate WLC parts catalogue issued? If so, a comparison with WLA engine part numbers would tell the tale.
What I'm trying to determine is whether H-D sometimes used an additional engine letter to identify special contract bikes like the WLC if it shared the same motor as the WLA. Or if the letter was also for a difference in the motor which was their normal practice when assigning an additional letter. But if WLA and WLC engines were identical, then the C was definately for the Canadian contract bike with its many chassis differences. Maybe H-D used letters in more than one way. Gotta prove it though.