If your going to go with the Hurst driveline conversion, it's based on the VERY early American Powertrain conversion, so the case (size wise) has little to no mods performed to it to fit the tunnel, plus most of the components are outdated in comparison to the latest offerings from the various 5 spd kit manufacturers...
If your looking for a 5spd Tremec, I'd recommend Silver Sport Transmissions, talk to Jeff Kauffman at SST, IMHO a TKO 600 .64 OD is the only choice in 5spds on the market
As far as the Passon 5sp, I don't think he has even offered that application (71-2 B/Ebody) yet?....plus the list for customers waiting is rather long from what I hear/read, his transmission and shifter pkg is currently $4995, if your converting an automatic you'll need all the other 4 spd accouterments to complete the job...
An SST kit depending on the options you select in regards to the transmission itself, as well as other option such as hyd throw out bearing, shifter options, etc, etc will run you anywhere from $3700-$5500, but you'll get a bell housing, clutch, flywheel, thrust bearing, transmission, crossmember/poly mount, speedo cable/gear, reverse switch/harness, drive shaft/yoke/u joints balanced to 10K rpm, plus assorted fastners/hardware for the install, shifter/hyd TOB will be optional, as will pedal assy's if needed, IMHO SST is one stop shopping if your going the TKO route...
mike