In a word, YES!! (not too mention odds on too heavy).
At only 70" in wingspan, a DLE30 or 35RA (or equivalent), or even something like a CRRC 26cc should drag it around with authority (the 3.15 hp one - there are two to chose from CRRC). This vid shows a 73" Sbach being flown on a 26cc RCGF motor (I followed his build blog as mine is the exact same airframe - but only green) and it looks more than up to it for sport flying - http://www.youtube.com/watch?v=eP8LZPGBLP0
That said, at an advertised weight of up to 13 pounds, the Extra does look to be somewhat 'portly' for it's size, so perhaps the 30-35cc option might suit best.