To summarize: So far there have been AFAIK three attempted builds using a Ritter block. One block was so bad machining-wise that the purchaser returned it for a refund. Another block was built and had a problem possibly unrelated to the block, but the owner is too busy to pursue it. The third block is the one in the link posted above.
Here is my opinion: Anyone who contemplates building a Ritter block better have a really good machine shop handy and expect to pay nearly as much in remachining as the block cost. This may be a little harsh, but it's in the ballpark.
FOR SURE you cannot buy a Ritter block, clean it off and put your parts into it expecting it to work.
The big bore block should go 467 cubic inches without breaking a sweat. Tantalizing, right?
R.