1976 Mercury Grand Marquis questions

Hi all,

I'm looking at buying a 1976 Mercury Grand Marquis. I've got a ton of
good quality pictures and the car looks mint. The odometer max limit is
100,000 kilometers and it's currently reading 15000, so the owner told
me he thought it has 115,000 km on it.

Question 1: is there any way to know how many times that odometer has
gone around? The car does look great, no rust, interior is beautiful,
but 115,000 is probably low.

Question 2: Does anyone know the safety issues of putting small kids in
an older car like this? The booster seats need shoulder belts which
older cars don't have. The thing is a tank though.

Much thanks,
SS.