Here are eBay links, just so you have a better idea of the options.
This is a
sprocket and CNC hub of the type commonly available on eBay.
These cost from $30-$60. You'd want a 1.5" probably to fit the rear hub of the Huffy - measure your hub OD.
Two other things to look for with these. A dished rather than flat sprocket is desirable because you can reverse it to get chainstay or tire clearance and the best chain line. And the recessed bolt heads are good for clearing your coaster brake arm.
And it's also good if the hole in the center of the sprocket is large enough to not interfere with the dust cover on your brake hub.
In the kit, you will get a
sprocket and rag joint. And chain. And it will be compatible with the drive gear on the motor.
I've described this already.
With either sprocket style you may need to bend your coaster brake arm slightly in two places to sprocket bolts and or the chain.
And now here is a
full kit that I know is pretty good (because it's the seller/one I bought), but there are some that are probably identical for $99 right now.
You get a lot with the kit, and there are tons of people and videos to help if you have trouble with any of this.
The sprockets all work with the #41 chain from TSC, which locally is $20 for a 10' length, enough to make 2 bikes. But to you, it's still $20.
You will need to be able to shorten chain as needed, either pressing pin out with a chain breaker tool, or my method, which is to grind the heads from the riveted pins, and then tap them out with a punch. So budget or plan for any special tools you need.
Hope this helps. I think everyone will agree the kit gives you a huge headstart on making your bike work.
Custom work can be rewarding, but it isn't always economical, and hardly ever the quickest path either.