David, Yes they are the correct cells but I use the Samsung INR18650-30Q they are 3000 mAh but are rated at 15 amp discharge where the Panasonic/Sanyo are only rated for 10 amps but are 3500mAh.
These batteries don’t have as big voltage sag on load like the Panasonics. (dropouts on take off!)
I wouldn’t recommend the Laptop batteries as they can’t deliver enough current.
I have a battery spot welder, so can make up packs for you.
Panasonic and Sanyo are the same batteries just branded under two different names.
Another option is to use a LiPo battery, 2S 1100-1500mAh