I just picked up from the side of the kerb a Lenovo M72E tower (not the SFF one). Had a G2020 which produced reasonable base & servo latency with 1 core isolated (Dedian Bookworm install with a RT-Preempt kernel).
Whilst it does have a parallel port header on board you'll need the lenovo cable, without it the Parallel Port doesn't show in the BIOS (I can confirm from first hand experience). Although it would be interesting to dissect it, apparently one of ground pins doesn't go to ground but goes to a GPIO pin on the Super I\O chip to enable the on board PP.
It does have 2 x1 PCIe slots that can each take a Parallel Port adapter card and a x16 slot.
The beauty with these is that a 3rd Gen i3/i5/i7 will run (can confirm i5 3470). If you want to run a dedicated GPU you will need to upgrade the PSU.
From one of the boxes in "The Cupboard Of I'll Need That Later" I grabbed a GPU and an SSD & Adapter I forgot I had.
So despite what some may say there still are PC with PP that you can get decent performance from.
Or you could just buy ALL the Mesa cards you can get your hands on...cos we know "He who exits this mortal coil with the most Mesa cards wins" hahaha
On a serious note this dude has some interesting stuff
www.youtube.com/channel/UCOKskywuQDlnV8yIkv67Gfw
