Macs and Bozaks were a very popular pairing in the fifties and sixties. They would often use each other's equipment to demo their products. With the Mac30 there is a good chance that your father's Bozaks were the model B302A/Concerto V. They came in several furniture styles and were/are very good sounding speakers. They later evolved into the B401 Rhapsody which used improved tweeters. Both can often be found for sale on E-Bay at reasonable prices. Bozaks are one of my all time favorite speakers.
Other popular Mac parings besides the before mentioned brands were JBL and Tannoy. Not sure about the used prices on JBL, but used Tannoy's are still very expensive.
Right now I have a rebuilt Mac240 driving a pair of vintage Klipschorns. If you have the room and the corners, they are still VERY impressive. Your MC30's have more than enough power to drive them and I've often seen them for sale between two and three thousand dollars. They are still being made and parts are readily available. Have fun and good luck.
