I know of a few options that some of the FFR guys do.

Turbocoupes used a hyrdaulic clutch setup. The whole thing can bolt into a fox body since the thunderbirds were fox based. Turbocoupe parts are hard to come buy though.

Mike Forte of Forte Parts ( http://www.FortesParts.com ) carries 2 different external slave assemblies and the mcleod hydraulic throwout bearing.