Just found this on IMDB.

http://www.imdb.com/title/tt0077594/alternateversions

...features a 127 min cut of the film featuring:

A large majority of Bruce Lee's original footage not used in the official release. This is most notable in the final three fights as there is now dialog between Billy Lo and Pasqual as well as with Hakim. The final three fights added up to only 10 minutes in the 1978 release, but the combined length of the fights in this cut is 25 minutes.
The greenhouse fight in the Hong Kong version is also in this cut along with an extended scene before the fight in which Billy Lo is training on his outdoor balcony as he hears banging noises from the other room. This is actually footage from Meng Long Guojiang with new sound effects added. Also, when Billy comes back to his apartment after the fight, he finds a note reading "Have you two made out your wills?" along with a phone call from Dr. Land in which all he says is "You bastard!" with a follow up villainous laugh.
The opening theme is replaced with an updated version of the Game of Death theme originally created for the Japanese film Bruce Lee in G.O.D.
The infamous "cardboard cutout head" shot shown in all other versions has been replaced with a close up shot of Bruce Lee from Jing Wu Men.
The even more infamous shot of the real corpse of Bruce Lee from his actual funeral has been replaced with a horizontally flipped shot of the outside of the funeral parlor with all of the fans standing outside.
All of the fake Bruce Lee yells have been replaced with real yells from stock audio.
The film's ending is an extension of the Hong Kong ending in which Billy Lo is arrested. However, the scene inter-cuts with Billy Lo (from the original Bruce Lee footage) walking back down the stairways of the Red Pepper Restaurant complex ending with him yelling out to the police in Cantonese "Help me!" One officer looks up and replies "Hurry down!" The scene ends with Billy Lo being taken away by the police, then fading to a tracking shot revealing the yellow and black tracksuit laying over top of a chair in an editing room and a narrator reading from Lee's Tao of Jeet Kune Do discussing "The Void".
The film also ends with a large number of bloopers and outtakes from Bruce Lee's original Game of Death footage.

I have not seen the compilation described above, but sounds just like the Game of Death project you are working on.