A couple of ways you can proceed here. Probably the cheapest and least work is to get another copy of the kit and cob the part you need from it. Barring that, you could build up the fuselage minus the nose, then graft in a piece of balsa or basswood that you carve to the final contour of the piece you need. This can become a master to either cast a new nose in resin, or vacuum form a replacement. If you go the vac-form route, you need to reduce the size of your master by the thickness of the plastic you are forming with. Both of those options require a substantial investment in equipment and time, so the kit cannibalizing is probably the way to go. One other option would be to build up the kit fuselage and glue in styrene blocks, then carve out the new nose in place. This is going to require you to be VERY confident in your ability to shape plastic! In any case, you are going to learn some new, and very useful skills. Dive right in there, and the best of luck! In any event, keep us all in the loop with your progress!