I would go with the dip strip in Allentown. A friend just had a '57 T-Bird frame done there and was very satisfied with the results.
Make sure that the chassis can drain completely so residual stripping fluid is not a problem. The car will be rinsed after stripping. Ask about a phosphate dip to inhibit rust while it's there.
I have had cars sandblasted and getting all the sand out afterwards is about impossible. And flimsy or thin spots will disappear.