Hi Puffin
I don't recommend Plasti- Kote paint. It's too thick and dries too fast.
The best for spray cans is the car paint. (probably from Halfords).
Start off with 'Red Oxide' and let it dry overnight. Then lightly sand over to smooth out the surface, then spray it again.
Wait until dry and then use Black Satin ( as Eddy suggests) for the lower hull. I have not seen White satin in my local store, so I used the whitest 'Car paint' I saw in the rack. (sorry but cannot remember which model car it was for). Believe me, there are more shades of white manufactured than there are snowflakes.

Don't forget that when you mask off the change of colour line, to over-spray with the original colour and let it dry, before applying the new colour. (it prevents paint bleed under the tape).
Don't forget to photo the process and show us all how you're getting on.
Cheers
Ken