Did LB make many four strokes? Like from the aluminum-deck days? Got a deck for mine - but it's steel (and used). I really like the LB design, but I am not a fan of two-strokes (sorry). I've had a lot of experience with them. Two strokes that is, not LB.
We had several at the cemetary where I worked, and didn't have much luck with them (even LB commercials)- except the aluminum-decked JD we had. Self-propelled, bagger, and it ran great. We even had some orange German thing, with a plastic deck. We needed a two-stroke, because the banks going to the road were so steep, it fried every 4 stroke in no time.
I have a 2005 (maybe 2006) Commercial 21" with a Briggs 6.5 HP. I believe by this time the 2 strokes from Lawn Boy were outlawed because of the emissions, and my machine is one of the last 21" staggered decks (they may have built it for one more year after), but the Briggs lacks the power and the awesome sound that the 2 strokes put out. I'm a big fan of the 2 strokes.