I don't know if your application requires specifically the TS-64, or if something else would suffice. The Masters Communications CT-30 is not a direct replacement for the Com-Spec TS series, but it does do most of the same things, especially in a repeater application. The major difference - it is NOT duplex, it will not encode and decode simultaneously. It does, however, have a far superior audio high-pass filter that doesn't exhibit the same audio quality reduction experienced by the TS series products. It's available in kit form to folks that like to build and save a few bucks. It's also available professionally built (by me) and tested for an additional fee.
The CT-30 is available paired with a quality noise squelch. This dual-purpose product is called the SC-50, and provides quality logic for noise squelch and CTCSS detection. The SC-50 uses the Motorola "MICOR" squelch chip for noise detection.
Detailed information on these and other products is available at Masters Communications.
Comments and questions welcomed.