You can do a FIAV bypass without losing the ISC. I wouldn't recommend removing the entite lower section of the TB and losing the ISC or doing a completer block off plate. I have been running a JB Weld version of the FIAV bypass for many years. Works great, no stalling, no idle changes when it fully warms up and no having to hold my foot on the gas to keep it running when I first start it.
Here is a pic of a proper FIAV bypass plate.
http://www.jmfabrications.com/site/c...fa7e959a4b.jpg
You can buy that one, make a plate like it or fill in the areas that are blocked off with JB Welds.