Use Test Enanthate or Cypionate@400-500mgs for 10-12 weeks along with [email protected] ED to kill the water retention. Couple this with a good diet and you should retain most of your muscle while dieting. You "might" want to add some EQ also.
Yes 250mg is good, more is better. Eq is going to give you a harder look and act as a plasma expander to give you more vascularity. End it 2 weeks before you end the test.