My current HT room receiver is only HDMI 1.1 and I get all the DtHD audio on my HD-A2.
HDMI 1.1 is all you need. HDMI 1.3 is not needed because all HD DVD movies have been encoded in Advanced Mode so the HD DVD player MUST do the decoding.
If you are getting a great deal on that used receiver and you trust the seller I would go for it. What is the brand/model and what is the asking price?