What components have you gathered together so far for this project. I still do not understand why you want to authentically replicate a semi stressed P4 chassis then fit a non load bearing engine of some description into it using brackets and try to fit everything else alternative into the P4 locations such as gearbox, suspension etc etc etc but are worried it wont be viewed as correct otherwise. Its never even going to be close to being regarded as anything P4 anyway so why make life so hard and the end result would be a very comprised vehicle as a result anyway. The P4 is about the look and the engineering, you can replicate the former but not the latter, however you can produce a decent chassis and running gear to compliment the body. With my own project, I love the look of the F40 LM which can be replicated but wanted it all Ferrari under the skin as well, there was no point trying to replicate an F40 chassis as it would have been a compromise hence why I chose a 355, same wheelbase so the body is positioned correctly but nothing under the skin will copy anything F40.