No need to get a new shifter with the TKO's.....they come with one (at least the 500/600 do, they come with a hurst already installed).
The G-Force is a direct fit drop in, while the TKO requires more such as a DS spacer, bellhousing, and crossmember mods. So you should take into consideration if you're up to the extra labor and parts to get it installed.
When I installed my TKO-600, I also had/installed a McLeod SFI bellhousing which has bolt patterns for both a T5 and TKO, but I would've had to use a $150 adapter/spacer if I used a '94/5 specific G-force. Also, at the time the cost of a G-force was only $200-$300 cheaper than a TKO-600 and that was using a used case for the G-force.