You probably could have the front drums/disks redrilled fairly cheap and easy by a machine shop. But the rear you would have to pull the axles and have them done also. It would be kind of a pain to redrill everything. Plus on the front youd have to have them drilled again when you need to replace them. I think wheel adapter technology and materials have come a long way from back in the day. Some people are still trigger shy of them from bad experiences in the past with inferior products.
That said the best option would be to swap axles and put BBP disks on the front BUT if you dont have the money for that, the adapters would be my next choice since i would have zero down time because i wouldnt be waiting on the machine shop. Just my opinion though