Tunes by mail (email) are a hit and miss proposition at best. If you're motivated, you could do it yourself. The OBD1 PCM's are not that difficult at all to tune. If the engine is basically stock, very little needs to be done. There are several, low cost, tuning programs available and the data link is inexpensive as well.

At the very least you will have to disable VATS (vehicle anti theft system) and, basically, turn off items that you no longer use, (EGR, Vac Canister etc) You need to make some decisions regarding fueling and air intake (MAF or speed density).

I opted to learn everything I could and took on the tuning process myself. Happy that I did, as I can "fine tune" the engine to get exactly what I want. The LTx are great engines that are reliable and smooth and make great power.

Here is a video of my tuning process. Engine is a 97 LT4 with PCM converted to OBD1.
https://www.youtube.com/watch?v=rhLUxzRg3EM