Yet another door handle question...
 

I've searched and can't find what I need. I seared off the forward stud on the driver's side door handle while returning it after replacing the trigger. I've drilled it out and am having a hard time tapping the hole, just pulls the magnesium out vice cutting threads and pulling the tap in. So, before I completely destroyed it, I bought a pair of used door handles, supposedly for my '78 SC. I put the lock cylinder in the handle, it's flush with the front of the handle, but doesn't extend far to engage the old lever that operates the lock or the two part lever that came with the used handles. Are there different length lock cylinders? Is there something I'm missing? Any advice would be appreciated.

Thanks,
Mike