It seems that the H55 would actually be the cheaper option in this case !!! Only need the bellhousing.
Actually, the honest cheapest option behind a V8 would be a used jeep or GM light truck 5 speed manual transmission and the Axis trans to splitcase adapter (AX15 is excluded as it wont work...
Do you have the Tremec, or are you buying it new? I am not seeing these were available as an offering in any domestic vehicles, so every one is sold as a new aftermarket unit? (unless buying used from someone who bought it new) Pretty steep price tag!!!!!