Sloping Z cut

Hi all, I’m trying to cut sink drainer grooves in a worktop using a bullnose cutter and whilst I can manage to cut simple grooves I’d like to be able to make these slope slightly down toward the sink. I’m sure I can alter the G code to accomplish this but could someone help me out with the correct way to do this please. The part of the code which does the simple grooves is here
Many thanks

N0110 T4 M06
N0120 G43 H4
N0130 G00 Z10.0000
N0140 S18000 M03
N0150 X250.0000 Y1160.0000
N0160 Z2.0000
N0170 G01 Z-3.000 F500.0
N0180 Y1525.0000 F1000.0
N0190 G00 Z10.0000
N0200 X310.0000 Y1160.0000
N0210 Z2.0000
N0220 G01 Z-3.000 F500.0
N0230 Y1525.0000 F1000.0
N0240 G00 Z10.0000
N0250 X370.0000 Y1160.0000
N0260 Z2.0000
N0270 G01 Z-3.000 F500.0
N0280 Y1525.0000 F1000.0
N0290 G00 Z10.0000
N0300 X430.0000 Y1160.0000
N0310 Z2.0000
N0320 G01 Z-3.000 F500.0
N0330 Y1525.0000 F1000.0
N0340 G00 Z10.0000
N0350 X490.0000 Y1160.0000
N0360 Z2.0000
N0370 G01 Z-3.000 F500.0
N0380 Y1525.0000 F1000.0
N0390 G00 Z10.0000
N0400 X550.0000 Y1160.0000
N0410 Z2.0000
N0420 G01 Z-3.000 F500.0
N0430 Y1525.0000 F1000.0
N0440 G00 Z10.0000
N0450 X610.0000 Y1160.0000
N0460 Z2.0000
N0470 G01 Z-3.000 F500.0
N0480 Y1525.0000 F1000.0

You are going to have to manually edit the program. It can be done when you post it in the editor. After that run the code through a separate code simulator like Camotics or NC-corrector to verify. Both are free and do a good job.