After playing around with the thermal core using non-aluminum resistors, and doing a little milling, and finding a little ceramic insulation I now have a working thermal core that can hold a temp near 234C.
My testing was the same block as the aluminum clad resistors but with a hold drilled and the resistor inserted (it was a square resistor) so that didn't work too well as there was lots of air around the resistor that stole the heat instead of heating the block. Even when adding aluminum foil 66C was the best that did.
The second test was an aluminum block made thinner in width but with a channel cut from the side for the resistor to sit in, and taped with kapton. This got me to 207C which is close but not hot enough.
My final test was using the same block from test 2 covered in ceramic insulation that is 1/2 inch thick that I acquired from a nearby fireplace store. This got up to the 234C that I listed at the beginning. This means I can finally get back to printing!