what will my slow stang run?

I too have the NOS 5115 kit. Unless you have a bigger fuel pump, then you're not going to want to go any higher than the 75 shot. 100-150 shots require more fuel pressure as well as fuel volume. So the stock fuel pump won't cut it. If you're turning 14.1 on motor...the 75 shot should knock it down 8 tenths or so. A full second might even be possible. Make sure your timing is on 9 or 10 degrees btdc. And you should run a regular style spark plug (NOT PLATINUM OR IRRIDIUM!!), but one step colder than stock. Let us know whatcha run.