Scarebird, is it safe?

Since you have a 1975 then you have the larger upper ball joints already. Just bolt in some disc brake knuckles from any later model car and you're ready to go. The late model FMJ stuff is still in the wrecking yards and will bolt right in.

Don't throw away those late model drum brake knuckles that you have! They are worth money to anyone who wants to run Viper calipers on the 11.75 rotors. You should be able to get $100 for the pair if the bearing surfaces are in good shape.