This is one of the very first recipes that I made when I first started diving into the cookbook Apicius as part of my research for FEAST OF SORROW. It calls for caroneum which is a bit tricky to know exactly what it might have tasted like but it was a reduced grape syrup of some sort. I recommend that you substitute sapa (sometimes called saba) or vincotto, which are essentially just different names for grape must, and either would be delicious in this dish. They are easily acquired at specialty food shops or Amazon.com.
Posts about ancient recipes:
Back in 1987, archaeologists discovered a treasure trove in a floor drain of the Roman Forum. This "treasure" was 86 loose teeth, all intact but with cavities in various stages. Three decades later, they've finally determined that they were all extracted by a highly skilled dentist of the time. Also of interest, up in England, researchers have pinpointed the advanced stages of dental decay in a young Roman toddler, to excessive consumption of honey.
Medicine was quite advanced in Ancient Greece and Rome. Surgeons regularly practiced lobotomies, Caesarean sections (didn't you ever wonder where that name came from?) and amputations, and were the inventors of tools such as forceps, catheters, scalpels and bone drills. Along with all of this fancy "technology" the Romans also relied heavily on herbs and the beneficial properties of food. Pliny writes (in addition to telling us how bees manage their colonies) that honey is good for afflictions of the mouth, pneumonia, pleurisy and snake bites.