Actually if you can do basic math ( which i probably cant ) it is perfectly possible...
you got 11 Equipment slots with each a maximum of 25% GF ( Like armor Helm Boots Offhand Rings )
which makes an total of 275%. Then there is the Amulet with a maximum of 40%. The socket of the helmet with 31% max. The Ferret with an additional 10% which makes after Adam Rise an Total of
356% GF WITHOUT the Hireling !!!! I read somewhere that you get 1/3 of his gf which should do another 30%. Dont know if its right or not but that would do a total of 386%
Quite much since i got only 290%.. but then again my equip suxx