Croesus
Adventurer
They play pretty well converted to 3e as well, just with expected levels being a little higher. 9-10 for G1, 11-12 for G2, 13-14 for G3.
Interesting - this doesn't match my group's experience at all. I attempted to run a small (4 character) party through G1 at 12th level and they ended up running for the hills. Just two giants nearly killed one of the main fighters in a single round of attacks. We were using 3.5 rules.
I suspect the only way the levels you list would work in 3.x is if you have a group that is good with builds and tactics, plus a much larger party than the standard four PC's. Dropping the giants down to their original hit dice, e.g., 8 HD for hill giants, would also help. Otherwise, I have no idea how the standard party beats the 20+ giants in the main hall.
And G3 is much tougher (based on my own memories of going through it during the 1E era).
Just my two cents...