According to old Road & Track tests, the volume of the 1750 GTV trunk was 9.5 cu. ft. and the 2000 GTV was 8.7 cu. ft. I saw an illustration that had the dims of the trunk as 37x52x13 (deepest,widest,lowest)for the 2000 GTV.
My error, the 9.5 figure is for the earlier cars not the 1750. I assume the decreased volume is due to the vapor canister in the trunk.
As to cut up bodies, I hear the preferred storage method is plastic drums in mini warehouses.