[I could be mistaken, but if memory serves I believe the original engine that
was planned for the Legacy was the Continental IO360, not the Lycoming.  It
didn't take long for folks to figure out that the IO550 would fit up front
just fine, and that has pretty much become the engine of choice.   Lots of
water under the bridge since those days, but that's kind of how I remember it.
  <marv>   ]

Marv,

 

That's almost it.  'Twas a turbocharged 360.  I flew that airplane, so equipped, and thought it was benign and did not let the Legacy realize its potential as compared to a 320/360.  Later, I flew the same Legacy with the IO550 and it was like night and day - the zip was back.. I think Lancair had always thought of the Legacy with engine options but I don't think anyone has put a TIO 360 in it. 

 

However, the FG Legacy should be fine with a TIO 360 since the empty weight would be much less and, if one so wishes, gobs of fuel could be stored where the wheels would go in the RG.  Hmmmmmm, maybe the 550 would be great in the FG....................