If this was about 3yrs ago, I'd taken you up. I have 2000 hours in C310's(mainly the r-model). Anyone that's serious about this should go for it. A C310 is a great airplane, learn its' systems, it's definately a neat plane.
I have to let my CFI side out and remind folks that I'm guessing this offer is going to be a split of Safety Pilot time, so make sure one of you is wearing the hood, work a lot on instrument approaches and working within the ATC system. There are a lot of great outlying airports in the ATL area that you can shoot approaches all day and not really affect the flow of traffic. I don't know if it's equipped or not, but I highly recommend NO AUTOPILOT. This is the time for folks to really build their hand-flying skills and a proper scan.
**Off Soapbox**
Oh yeah, have a great time with it, sounds like fun!