Here is the million dollar question.
I came across an interesting portrait of Yinyuan in an auction page. It was painted in the year Xinmao 辛卯 (either 1651 or 1711). The style is so different from the portraits by the Kita family and looks more like the literati painting style. One source said that it was painted by another Chinese monk Donggao Xinyue 东皋心越, for whom van Gulik 高羅佩 published a book in 1944. ( See 明末义僧东皋禅师集刊.) But Xinyue died in 1696 and in 1651 he was only 13 as Tanaka Chisei 田中智誠 osho pointed out. Tanaka osho also confirms that Xinyue did paint Yinyuan's portrait in 1680 but it was a copy from a previous painting.
If this was indeed painted in 1651 before Yinyuan left China in 1654, this is going to be a significant discovery.
Anyone can tell me more about this painting? Here is the link and the images.
http://bbs.artron.net/thread-2906694-1-1.html
http://bbs.sssc.cn/viewthread.php?page=1&tid=2356588
