We have two Howard DGA's flying on our field. And, one an hour away in Little Rock, AR.
You probably know DGA stands for "Damn Good Airplane." Thirties humor I guess.
What a classy, nice flying bird. Big, lumbering and arriving in style. You already know how good the engine is.....
I find with all the room in the plane, it feels tight on leg room and I'm not a fan of the pushed in panel. But, they fly really nice and otherwise roomy and comfortable. If they're too heavy on the ailerons, it's likely the 70 year old bearings need replacing and cables retensioned.
It's a kitten on the ground, but the gear will rebound heavily (known to slingshot) if you plop it in.
I would recommend you really go see one. And, why don't you try and reach the Howard Club? They have a flyin every year at Cable, WI USA the week before Oshkosh, then they fly to Oshkosh.
You already know the fuel burn. Plan 130-140 kts, depending on altitude.