Nice bass but 20-30k to cut it down and fix it properly. I can see the bass bar area is sunk in a bit there in your picture. I would suggest Robbie McIntosh for the job. He's like on of the best. He fixed my Hart top and restored my Marconcini.
I see the 1883 in the rib there, not 1886. I had something similar on my Gilkes English bass as well in the rib.
Now, in talking with a few people in the business, we all agree from the varieties of basses SOLD by Lowendall that they vary so much, it is more likely that they BOUGHT the basses from Bass making shops and re-branded them.
There were some great basses makers in Germany at that time and even the Cello model that I have now seen about 4 of them, no two look the same.
Here is the inside of MY bass during restoration a few years ago which was done completely by Arnold Schnitzer himself..