Bill -

Suggest you check McMaster-Carr under "sleeving". They carry teflon spiral wrap
for wire bundles under the name of "helical bundling wrap". It's good up to 500F
and comes in a variety of sizes.

For wire ties you can get "heat stabilized nylon" or "Tefzel". Tefzel is good
upto about 300F but it's VERY expensive.

Ted Stanley - A&P-IA