I recently had to move to a long putter for medical reasons. The anchoring ban has made finding options difficult at best.  I have an older model Maltby mallet putter head with a 90 degree bore angle.  What shaft should I use (single bend, double bend, other) to get to a 79 or 80 degree lie for a 46 inch length putter?  I understand that to get this length may require a standard shaft with a shaft extension.