1. no seat belts in the back, no headrests
2. poor brakes (especially if you were seduced by the size of the cargo area and loaded a bunch of weight in it)
3. inadequate power (could barely to 65)
4. would tip over if turned too sharply
5. don't even think about hitting anything head on, just a bit of sheetmetal there
6. highly susceptible to cross-winds
On the plus side, it was inexpensive to maintain and ran for decades. I finally sold it for my dad, and he asked me if I was nostalgic for it. I said no, I was just happy we never had an accident in it. My dad gets the credit for that, he was an unusually careful driver. Never hit anything in 70 years of driving.
I know times have changed, and what was acceptable in the 60's wrt car safety has changed a lot, but still...
If you want to drive something that drives like a sports car, get a sports car for the weekends.
[1] I remember reading about a volkswagen bus that had been modified heavily with Porsche components to the point it could drive and accelerate better than any van had a right to.