Thank you all for the suggestions. Ahem... I mean royalty fee.... but let's think about that later not until the kit is in the final phase (and worry about their laywer's letter), shall we?
To clarify, I am using the clay to just study and understand the shapes. The nosecone/cockpit does feel kinda heavy and ~soft~ (held in my hand it feels kinda like a dildo, LOL!). Anyway, for the final master sculpt I am ordering jars of MagicSculpt, which is self-hardening and no worry about getting sloppy. I just need to make some initial framework, could be just cardboard hot-glued together. Does not matter, only the final shape matters a lot.
For scribing the lines let's worry about that much later. I am in dental school so I have a lot of scribing and drilling tools you see.
Still, the difficulty is to nail the shape, proportion, angles of planes and curves etc. The line art appears simple but there is actually a lot of information to extract with even more open to interpretation. That no amount of CAD can help with (as I believe that's what Hasegawa and Yamato did with), and I believe only with a pair of sculptor's hands and an artistic instinct will it be done right.