Harry,
From what I remember (this is from last summer) the 1x8/9 frame and the Quietline frame is slightly different in the engine area.
On the 1x8/9, there are flanges that come out from the bottom frame rail, toward the center-line of the tractor, this flange is what the engine bolts to.
On the Quietlines, this flange is not as large, and does not have the area to bolt the engine to. I am fairly sure, it you wanted to eliminate the Rubber ISO-Mounts, you would need to use the solid metal replacement mounts. To mount it like a 1x8/9, you would have to weld material to the frame to make a place for them to bolt. If I were going to eliminate the Rubber ISO-Mounts, I would go with the solid spacers, so everything lines up correctly.....
However, on both of mine, a have a good set of the original (70's) style Rubber ISO-Mounts. They work very well, and to make sure they survive, the cradle mod has been done to both of my quietlines, and Dad has done the mod to his quietlines also.... I wouldn't take the time to pull the engine and replace the ISO-Mounts and not do the cradle mod.....
Another "mod" that we do, is while the engine is out, we replace the axle pivot pin, with a "custom" bolt (Correct size bolt with the head ground down to clear the oil pan) and tighten the bolt, to remove most of the slop from the front axle, due to the C-Channel spreading over the years..... the 82 series have a bolt factory, but with the flat bottom engine, the clearance for the oil pan is not an issue........