Yep. What you're seeing is right. The actual "firewall" (really it's the forward fuse bulkhead, I suppose) is "square" to the fuse jig construction, apparently. Both of mine were that way. The Upthrust ends up being built in when you assemble the motor mount firewall, and the side pieces set that. I know it is counterintuitive to see that upthrust, but the stab sits slightly positive relative to the wing, and the wing seems positive, also.

I've built a ton of pattern models through the years, and hardly any had upthrust - but Mr. Park knew what he was doing. With the thrust as built-in, these planes fly exceptionally well. I wouldn't have believed it, but it is true.

Build it stock, with the upthrust the side plates build in - it will be fine.