Here's a picture of the inside. The stones are 20"x20".
If you notice the little metal rod sticking up from the bottom of the door, that is the temp sensor or the thermometer I installed on the door. When I did it I never thought ahead that it would be sort of in the way of sliding pizza in and out until the first time I went to use it! I was like 'Doh!' (excuse the pun). But it has turned out not to be a big deal. Just takes a little more finesse to go over the top of it.
Regarding the natural gas / propane conversion. Yes, it now has a propane regulator on it. Despite it being a pretty simple process to convert which from what I remember involved only changing the regulator and the gas nipple from NG to LP, I am not an expert at that stuff and hired the service company in CT that is authorized to maintain Blodgett ovens. It cost me a couple hundred bucks but the technician has been in the business a long time and completely went through the oven. He even told me what parts if any could go bad on it some day and what the symptoms would be. It was really cool because he loved the oven and had never seen the exact model before. He even called his wife to tell her about it while he was there. I think he would have bought it off me if I were willing to sell it to him. He gave me his cell # and told me I could call him any time with questions. Great guy.
Regarding the higher temperatures. The temp sensor on the oven is above the top deck right near the exhaust opening by design. The temp adjustment on the oven itself goes from 500-650. When I have it set to 650, the reading on the lower stone from my IR thermometer and my door thermometer are about 700. The temp at the exhaust is likely closer to 650 and accurate. The temp control definitely works because when it senses 650 at the exhaust it automatically shuts the burners and relights them when the temp drops a bit. So since this is all by design, I have no doubt its made to handle 700 at the lower deck with ease. It's a good point though if I were to try and trick it to go higher. Like I said though, I'm perfectly happy with how it cooks now. These pies are not 1 minute pies though by any means. More like 4-5 with opening the door occasionally and spinning them. I'm not the type to get hung up on that though.