My son and I are building one of these right now. We are solving the tail heavy condition by installing a BAE on the firewall. That is a Magnum .91 four stroke. We moved the firewall back about 1.25 inches, so the prop washer was not too far in front of the cowl. We have not installed the radio gear and pushrods yet, but our estimation is that the weight and balance will be just about right without a lot of lead weight.

If you do a search, there are several threads already posted here about the Seagull Zero, a lot of good information. Like throw the supplied clevises away and stuff like that.

Regards from old bird.