The BPPC configuration you described is the best you can get for an A1200 currently. You can only get them second hand since Phase 5 went out of business several years after Commodore went out of business.
There is another PPC accelerator for the A1200 in the works from ACK Software Controls that will run AmigaOS 4 called the PowerVixxen LT but it isn't in production yet. For more information about it there is a log from an IRC chat with its designer
here.
