If building a new turntable playback system, you should consider the new Rek-O-Kut S-260 MKII extra long arm.  There are very few modern tonearms that actually have 16" transcription disc capacity.  Few less that are true 12" (305 mm) in effective length.  Those available else ware cost many times the price of the S-260 MKII.  This extra length also has advantages for 12" LP records, in that there is much less tracking error. Unlike vintage Rek-O-Kut arms, the S-260 MKII utilizes standard removable headshells to facilitate switching cartridges and styli, precise tracking and anti-skating force adjustment, a damped cuing arm, and lower mass.