Thanks for the info guys. I have plenty of room for more cement and that refractory cement is what I wanted but could not find it near my location. I thought it had to be refractory cement and that regular cement would not work well but it may be worth a try. Maybe just a 1/4 or 1/2 inch layer added to the plaster I already have. Thanks for the ideas. I will post the first firing of it when I lite it up.

Cheers, JR