3/4" tools on a 14" lathe? You must have money to burn on inserts or be taking some very heavy cuts!
If you want to use the larger holders, mill 1/8" off the top. Sure is cheaper than buying a CX size post and all the holders.
BTW, Not many people would know that PM is Precision Mathews. IOW, a chinese clone of a 14" clausing.
JR