Hey I am in Clemmons, don't know where you guys are. I have been flying a Predator 2 with both a Jett super sport for weekend practice and with a Quickee Jett for 428. I flew it at the NATS and it handled very well. You should have the cover for the top of the stab. i had to sand mine so that it would fit. Any spaces, unless too big you should cover with the 3M racing tape sold by Darrol Cady for example. With the space below the stab I just filled it in with thick CA and made a fillet with accelerator, and it has worked fine. Make sure you reinforce the firewall and the hold down plywood in the fuse. I used small triangular stock, CA and 20 min epoxy. Good luck,
Luis M.