Your casting looks really nice, but I do have a few concerns.
First the simple one. How high is your dome? If you plan to fire from bellow like I assume you do I think it is gonna be way to high. Top heat is gonna be your biggest issue, as it is with all ovens heated from the bottom, and keeping the dome low as possible is gonna be key.
Finally, what type of cement did you use to tie that all together? I'm gonna assume Portland, but am hoping it was calcium aluminate or something else refractory. Lately it seems like lots of people want to copy the frankenweber, and I have no idea why. The oven is poorly to nearly un documented and what little we do know includes that fact that it has been rebuilt at least once. The use of perlite and portland cement for the oven dome goes against thousands of years of knowledge and thousands of functional ovens well documented online. One guy does it with questionable methods and results and suddenly everyone wants to follow suit.
Outside of that I think I basically voiced my concerns in my post a few up.