Motors hidden away in machines are often neglected for many years or a life time. Out of sight out of mind. Without getting greased.
So yeah, I think a sealed bearing could work for many years. And as the current owner, you'd be aware.
Taken the trouble that you have to do a real nice job, I'd be inclined to try to install without a dust shield if possible. Plus some future owner, who might take care of proper maintenance, won't try to pump grease into a sealed bearing.
You could either go with sealed or shielded bearings... If it were me, I would get some shielded bearings and pick the shield off next to the grease port and lube every year as it is supposed to be lubed, but that is just me.. I am old school.. lol.. Cheers from Louisiana.. Ramsay 1