Recently I upgraded to brushless power in the WL Toys 144001 as you can see in the below article which is also relevant to the new WL Toys 124018 and 124019:
WL TOYS 144001: ULTIMATE BRUSHLESS UPGRADE GUIDE
Performance is so much better than stock and battery life has increased by over 50%. I much prefer this smaller brushless that the larger 3650 size that are usually limited to on road and speed runs. The install is fairly straightforward but you need to slot the motor mount to set the mesh on the smaller 17t pinion gear and this can be tricky. Good news though, I've found a workaround where no machining nor tricky gear mesh setting is required.
The 144001 uses a 0.7 modulus gear pitch and is very rare for pinions. We are typically limited to the very large stock 27t pinion (way too big for this application) or the 17t pinion from the WL Toys A959 / A969. The 17t pinion offers an excellent ratio for the 2838 and 2845 motors but you need to mod the motor plate as mentioned in my original brushless upgrade article.
Good news though, I've found that using the stock 380 motor mounts on the motor plate you can use a 15t pinion gear. Up until recently these have been impossible to find but I've done a LOT of testing and have found three options for you.
Option 1: 15t from Hobbyking
Hobbyking still have some old stock of a 15t 0.7m pinion that we used on certain helis but it is not a bolt on option - as it has an oversize 5.0mm bore. Because of this you need a 5mm to 3.2mm reducer which is available here. You may also need to file down the grub screw a little if it fouls on the mount. Please note this may now be out of stock depending on warehouse
The larger bore means the pinion collar is larger. It fits but the grub screw needs reducing in length just a little.