The Super Kaos Jr is not a resizing of the Super Kaos. It’s an original design of a 40 size Kaos published in RCM magazine, so look for the correct plan if you want to build it.
You can have your ribs cut for either nosewheel or tailwheel. You also have the choice of standard ribs or alternate, as detailed below:
These have a long leading edge for use with a notched diagonal leading edge stick as shown on the plan. They also have 3/8 x 3/8 spar notches for use with a big fat balsa spar.
These ribs have a shortened leading edge for use with a flat 1/4″ balsa leading edge stick. They also have 1/4 x 1/4 spar notches for use with hardwood spars.