It is said in the pilot that their top speed and sustainable cruise velocity is warp 9.975.
At that speed 75,000 light years would take 14 years 7 months. Even stopping for fuel and maintenance every 5,000 light years would probably only add a year or two.
Even warp just 8 would be 73 years 3 months.
The Enterprise G could cover it just 2 years 4 months.