I don't know about being able to turn the harmonic balancer with one hand. On the 360 I pulled out & the new one I just put in, it was pretty tough to turn it over, especially by hand. I would check that out.
They're definitely not cheap to rebuild. I was going to rebuild my old one, but found it would be quite a bit cheaper to buy a new longblock & go from there. It seems that parts are usually about twice as much as Ford or GM parts.
1983 CJ7 AMC 360, T-5, Dana 300, Dana 30, AMC 20
Warn XD9000i, RE hand throttle, 1" body lift, OBA