Capture PPS timing signal into PC with minimal latency
Assuming (by the comments) that you actually want to build some NTP server with a 1PPS input, you should perhaps look into a Raspberry Pi with the rpi_gpio_ntpd installed. (Also available here.)
This lets you synchronize the timebase of the RPi to an external source connected via one of the GPIO pins, (AFAIK) directly using GPIO interrupts, which sounds about as good as you can get.
Someone has also built this with a GPS receiver, and they do have some real-world data on the rather good level of accuracy you can get with this inexpensive setup.
The only problem left to solve would be level conversion from TTL to 3.3V CMOS input the RPi would accept, but this sounds trivial enough.

Another option would be the use of the Precision Time Protocol (if your NTP server supports this, which isn't unlikely), which uses hardware timestamping in network cards and switches to figure out the latency between two endpoints.
This means your network cards and the switch in-between (if present) would have to support this. Do check if your network cards support this, many do not. However those that do support PTP can be still affordable (like those based on i210-T1).
But this is a standard off-the-shelf solution that is likely to work.