Mine was 7lbs 4oz built from the Kit. I did a couple of things to make sure was as light as possible, but nothing drastic.

A YS110 was an insane amount of power for this plane and I liked it alot. Even if it had been 8lbs it would have been fine. So, IMO, a 4 stroke 91 would be great. A 2 stoke 91 would be about the same power as the YS110...so that's OK too. I would opt for the four stroke because I like the low-end power and not having to build a mini-tunnel for the 2 stroke muffler.

I would not have used standard servos just because of the large surfaces. But, it may be OK with just a high torque on the Rudder.

Richard

I used a 1/2" wide CF strip top and bottom on the wing at the high point of the airfoil after reading of some wing failures. There is no spar or joiner, just the balsa skins joined with fiberglass and epoxy.

The WB60 really was a fanstastic flying airplane. Mine went in after a few flights due to an elevator linkage failure...