This is about 1/5 scale. Full-size J-3 has a 36 ft wingspan, or 432". Divide 432" by 88" and you come out w/ 4.91, or about 1/5.
Aside from the fact that it doesn't look much like a J-3, at least in the one picture on the site, other than the fact it's yellow w/ exposed dummy cylinder heads, I can't imagine that it would take anywhere near a 1.20 to fly it. A 90-sized 4str or a 50- 60 sized 2 str would be plenty. A J-3's really than a glider w/ power. The full-scale J-3 has a 65hp Continental.
But Seagull makes pretty good airplanes, and I imagine this one will be well-built and fly well; it's just that if you want a scale J-3, you can do a lot better.