All depends on how much you have left after you stop at 5800. If you advance the throttle fully what is the rpm? If it's 5850 or 5900 then no, if it's 6K plus then yes go with a 19 itch of the same design. By your numbers you are running a decent prop as you are right at 10% slip. If you use a 19 and get the same slip you would be doing 47 at the same 5800rpm.
Remember your time to plane will likely be slower.