from my research with my EZ30R project there are 2 main types of H6 and someone correct me if im wrong:
EZ30D: 2999cc DOHC, 220ps (161 kW) @6000rpm, 289Nm@4400rpm. Bore 89.2mm, Stroke 80mm. Compression 10.7:1. This version uses one exhaust port per head, a cable throttle, variable intake geometry, cast aluminium intake manifold, and has a 6500rpm rev limit. It was only available with an automatic transmission. Found in the 2000-2002 Outback H6 and Legacy Lancaster 6.
EZ30R: 2999CC DOHC, 245ps (180 kW) @6600rpm, 297Nm@4200rpm. Bore 89.2mm, Stroke 80mm. Compression 10.7:1. This version had one exhaust port per cylinder, a drive-by-wire throttle, a black plastic intake manifold, VVL and AVCS. It was available in manual and automatic unlike the old EZ30D. Found in the 2003-2009 Legacy 3.0R, Outback 3.0R and 2006-2008 Tribeca.
and then there was the EZ36D but unless your looking at 2010 legacy or outbacks ill leave that out.
i would get the 3.0R if i had the moneys but of course thats the big thing. The old EZ30D is still a good engine just doesnt have VVL or AVCS and since u are wanting auto then it should be all good in the hood.