I'm building a Ragwing Stork RW20 and it is very robust. It can be built in the 600 -650 pound range if you go with the lighter tandem version (RW-19), use a lightweight engine, stick to the plans and don't add extras. If you are really careful it can be done under 500 pounds, but that's with no brakes, side windows, etc. and a 2 stroke. I'm 6'2.5" and 220#, and Roger Mann is even more, so join the club. Occasionally unfinished projects come up for sale. Roger has a video of the planes flying and they certainly perform at the low end of slow flight/extreme STOL. They are rather draggy so top speed is not their virtue. The speed record is in the 80's, with cruise in the 60's/70's depending on how clean you make it.
I suggest joining our Ragwing Stork listserve. We have about 450 members with many builders. So between builders and Roger you can get questions answered.
There is also a STOL King listserve. I'm a member of that also and have the plans. One just flew a few weeks ago and can be found on you tube. The plans are more complete on the STOL King, but it is much more complicated and requires welding skills. Currently you probably can only find STOL King plans used and the only support is from other builders.
If you are a good welder and can handle a complicated build the STOL King would be good. If not, the RW-19 is the way to go and it is much cheaper to build.
Another possibility is the Just Highlander. You can buy it with the welding already done.
Gary Van Meter