A very nice idea for a thread, Ryan! Imo, mocking up models is essential before starting a build. Unfortunately I rarely take pictures of my mock-ups but I have few...
Heres my ´41 Lincoln Phantom Fastback after Making some body work:
When I built my version of the Supernatural Impala some years ago I tried some wheel/tire combos to check the custom car or pro touring potential of the 4-door Impala:
A quick mock up of a ´49 Merc I want to do in the near future:
And finally the ´68 El Camino I going to paint next week: