Re: head tube replace
Silverbear I've used 1" threaded mountainbike suspension forks on a couple of my builds, readily available as used or takeoffs on ebay. One listed today was buy it now $13.95 course most are $50. & up. Most are set up with bosses for rim & or disc.
Be aware that the lower bearing race isn't always included on even new forks and the race on used ones may not be suited to your Schwinn headset, if you run into that problem pm me and I'll help you source one out. Good news is you can run suspension & rim brakes with your electric front drive. Older electrics often didn't have disc rotor mounts. Rick C.