Not to be critical here but the size of the ht engine in relation to the bike is not correct, the chain guard on the cranks shows to be almost as big as the engine which is a bit off, again its a nice bike and can be motorized with the right fabrication, tools, parts and skill, but unless you choose to go with a friction or rack mount as Tom has mentioned you will have what will likely be a much bigger project than you may want for your first build.
Some will not agree with what I am about to say here and thats fine but many of us have proven it to be a good route for a first build and one that can be modified and improved as you learn more and have the funds to do so.
HUFFY CRANBROOK or any variant, hub and all bearings need to be cleaned and grease with high quality grease, put you a wode comfortable C9 cloud nine seat on it, maybe some 26x1.95 smooth rolling tires, a front calper brake and you will have an excellent bike for the first build that you can build on and learn all the reliability tricks on.
Some think you must have a high dollar bike for it to last and be relation able, simple fact is that is bunk.... nothing wrong with the high end bikes if one can afford them and thats what they want, but for most average builds just a well put together middle of the road or even bottom of the road will do just fine and they are cheap to maintain because there are so many donors out there.
Just my $0.02