If you're using a fighting butt on a rod it's very easy to turn your uplocking reel seat into a downlocker, just by inletting the fighting butt to accept the reel seat hood and if available add a trim ring to clean up the transition from screw fitting to the grip.

Here's an FRC ULM6 in Antique Gold as an uplocker

And here as a downlocker with a mini rubberised fighting butt and trim ring to match the reel seat hardware. Note the grip doesn't need to be inletted now!

For the FRC ULM6 visit Here

For Fighting Butts visit Here