RE: How much thrust do i need for a custom jet?
Yes that will do nicely. It's not about making it faster. It's about keeping the wing loading about the same so that your stalling and landing speeds do not need to be crazy high.
And anything you can do to lighten your version will make the model fly faster, turn harder without bleeding off as much speed or snap rolling out of the turn and generally make the model more fun to fly.
Best of luck with your design.