Update:
Went back to mechanic, and changed the slave cylinder, and rebuilt the master cylinder. Result, no change.
Backtracked our steps. Concluded that the OEM cush drives were very worn out, and when new chain and sprockets were changed, aftermarket (from Tim at Pashnit) cush drives are way harder material, and have no slack right now, thus everything in the drive train is snug, resulting in harder than normal shifts into first gear.
New clutch, slave, and rebuilt master cylinder are things that were original, and with 100K, I don't feel bad replacing them.
Now we'll just ride the bastard. Carry on.