Kudos on the VO2. I don't have a clue about that stuff. Never had it measured.
It looks like the cost to get into the park is $35 -- annual pass. Click the link to see all the pricing options.
http://www.stonemountainpark.com/tickets-pricing/
I drove out there today and parked in the SM Marta parking lot (near 4th St and E. Mountain St). Its a few blocks from the west gate (bikes and pedestrians only and free admission). I could meet you at SM whenever you'd like, as long as I have an opening in my busy schedule
(appt tomorrow, doctor Wednesday, eye doc Thursday).
If you want to add a few more miles you could park in Clarkston. There's a huge church parking lot that many cyclists use (about 6-7 miles from SM). Or you could park at the church next to the cemetery on Ponce in Tucker (about 2 miles to SM). Or you could park somewhere in the industrial park between Tucker and SM (about a mile from SM). I can meet you at any of these locations.
I need to get back up to speed too. I was in Florida for 2 months (Feb and March -- snowbird??) riding on the
FLAT Withlacoochee Trail 
so my climbing muscles have gone into hibernation.
Send me a PM when you're ready.