The only other option I believe is to drill out the rear of each brake mounting hole on your frame to take the new recessed nuts. This is not too bad on the forks as you can remove them to make access easier, but the closeness of the seat tube makes drilling out the rear more awakward.
This is actually the best option. Depending on your brake bridge you can drill it all the way through if theres enough meat there. Alternatively you will need an angle drill to get in from behind.
There is another option for the rear and that is to replace the fixing bolt on the rear caliper with the fixing bolt from a front brake (not sure but think that most Shimano Dp's from the same era will fit). This will then feed all the way through. Forks are easy to drill as mentioned.