I was going to finish this project by the end of last year but am still struggling. Sorry but I am going to finish by March now.
By the way, I have found a testimony that the J8M was reverse-engineered in a book titled "Syusui" written by Hisamitsu Matsuoka - a former Mitsubishi engineer like this.
"Around this time (in the summer of 1944), Mitsubishi's fighter design team for the navy was so busy with the improvement of 14-shi interceptor "Raiden (J2M)" and the development of 17-shi carrier fighter "Reppu (A7M)" that they felt it almost impossible to undertake the development of tailless rocket interceptor which they had never experienced before.
Moreover, although there were some data which were brought back from Germany by Lt. Colonel Iwaya, they were not detailed enough to be used for the production of actual aircraft including the engine as they were.
Contents of the technical data brought back by Iwaya were nothing more than these.
1. A very simple design manual of about 20 pages in A4 size, a piece of photo showing rough 3-view of aircraft assembly (with no numerical value), a rough cross-sectional view of the main wing in cabinet size photo (with no numerical value of the airfoil either).
2. A simple instruction manual on producing and handling the chemical solution, a report of combustion comparison tests of several types of chemical fuel injection valves of about 20 pages in B5 size (with brief explanation of the principle and structure of the rocket engine) and a set of documents on ingredients, performance and production method of chemical solutions."
Shinpachi's J8M at work.