Hay Clark,
To be honest...the only kit of the Beech 18 was a gas engine twin kit...over 100". I've not seen a Twin Beech kit ever...and I've looked for years. I flew these on a Fed-X run and have many years in the cockpit, but never a kit in the .20 to .40 or .60 range available.
There are plans available, but that's about it.
Soft Landings Always,
Bobby of Maui