Cleaning is always tricky. If heavily encrusted I usually start with a plastic putty knife, expired credit card or anything else that reduces the chance of damaging the surface. I never use solvents at first...too risky, just warm water and liquid dishwashing detergent. As far as getting under the car, getting it on a lift or over a pit would be nice, otherwise squirming on the ground is about all that you can do and is how I mostly get under the car.
I did not find anything on the Radiator Support or the Cross Member; all original but just didn't survive. I did find writing on both of the front Aprons but that's all. The Driver Side has 3 zeros at the bottom, 2 threes and a faint 5 or letter S. The Passenger Side clearly shows 2 two's at the top, just below are 2 more smaller two's and below that 2 ones. Black Paint obscures the two's and ones; unfortunately the photos I took after cleaning away the paint did not develop properly and I never took any more of those areas.
The stripes, though faint, were clearly stripes; very straight and side-by-side with just a little space between each stripe. The Leaf Springs are in storage so I couldn't take a quick peek but if I recall correctly the colors were Green, Yellow and White and only on the Passenger side Spring between the Spring Perch and Shackle. Unless I can get a clear photo however, I can't substantiate this claim.
Ray