A great idea, creating two aeroplanes by manipulating one already existing. Sadly the resemblance to the originals isn't great, but that's always a problem with frankenplanes. Whilst I approve of the idea wholeheartedly, and enjoy flying them too, there are some aspects that need attention drawn to. yes, I know, I'm nitpicking again, but if it helps create better models in the future then I've done something useful.
Firstly, the D510 is a little overpowered. The climb rate is closer to that expected at the end of the Second World War, not the beginning. I suppose that's nothing to sneeze at - at least it doesn't have the asthmatic UP compatible FM's - so I'll still give it 8 out of 10.
Secondly, the wing shape of the D510. Okay, it's just the lower wing of the B534, but that's the entire problem. It's too small. If you look closely, if this aeroplane was real, it would be tail heavy in flight. And with a restricted wing area, the wing loading might force the pilots to land at dangerous speeds - if they can take off before they get to the end of the runway to begin with. In my view (you may disagree) the wings need to be scaled up a bit and moved aft a little.
The same problem exists for the D570. From some angles the wing size looks a little silly. Biplane wings are smaller because they can afford to be - you have two of the things instead of one. Again, a little scaling up might look better.
Right, I've said my piece. I'll let the community get on and enjoy the mods. I know I will.