I would vote to go the DA8 route. An advantage is that you can run new SRAM 8 spd cassettes and chain which are very reasonably priced and readily available. As previously mentioned, DA8 is nearly as bulletproof as they come. I have a DA8 group from 1991 that has been well maintained, but battle-scared. It still works great. The SRAM cassette is much lighter than the original Shimano and shifts as well or better.