No idea about the canbus stuff but I think the simplest thing to do would be to run a second oil pressure and temp sensor so both the Holley and Invision to be happy. If the Invision used 5v signal based sensors you could tee of the output and feed it to both the Holley and the Invision but it looks like the Invision uses the resistance based sensors so that wouldn't work.
You could feed the Invision the tach signal from the Holley and if you're using trans control with the Holley (Terminator X Max or Dominator) it could give you a speedo signal. The normal terminator X doesn't do any trans control and won't even look at the speed signal out of the box.
Alternatively you could just use a Holley dash screen right?