Did a bit more digging into my proposed T-T setup for PSK/digi modes use. Looks like the Signalink USB interface will handle the I/O duties with an appropriate set of radio cables. I'll need some way to remotely control the Omni VI and one of the Paragon IIs and N4PY's ICOM software appears to be a good candidate for this. Maybe the free version of HRD...needs to be a Windows-based solution for now.
H/W interfacing will be another matter. The Omni VI and the PSK-configured Paragon II will have 253 Autotuners attached to them and this requires the rig's DB25 port for tuner-rig communications connection. So...I have to use a level converter to access the radio's one-wire controller. Looks like an ICOM CT-17 is a direct replacement for Ten-Tec's 305 and I just happen to have a couple of them.
The Omni V and the second Paragon II are also going to be interfaced to the computers which control the other rigs, and their DB25 ports are available. My aim is to be able to control the entire shack from my home office desk, and have the ability to jump bands at the click of a mouse...with the tuners tracking these changes and adjusting themselves accordingly.