If someone finds in themselves the interest to model this puppy, here's some stuff that was not in the PDF linked in OP.
It doesn't seem to me like the P-51 fuselage would be sufficiently good match to make it a viable frankenplane. Especially the radiator deviates from the P-51. Not only is the Me-309 radiator much more forward than the P-51 radiator, it's also fully retractable by the looks of it, while the P-51 had a fixed radiator scoop mostly behind the wing structure.
The wing plane form resembles late Bf-109 wings, but internal structure must be significantly different to support landing gear hard points that far off the fuselage. Ki-61 wing could technically do as a template, but the other details of the wings don't look much like the Ki-61 at all, especially the bulges over the wing which seem to act as fairings for some hefty outboard cannons.
It also looks like this plane would have had much more armament than sources claim - each wing seems to have three gun placements (two on the inboard section, one on the outboard) and the fuselage seems like it has two more guns above the engine.
Additionally, the engine specified - DB 603 - would have left a provision for a nose cannon, although none of the drawings seem to have that.