I bid on and won the Hipo block above, the seller and I subsequently(and during the auction) found out that the caps were mexican, not Hipo. The seller has released me from my obligation to buy the block and has been very easy to deal with since we both started getting feedback about the blocks potential authenticity as a Hipo. Also the seller was labeling this based on advise from an associate of his.
Based on my experience dealing with the seller all I can say is we both learned a little more about 289 blocks, and he deserves the high rating he has on ebay.