I can’t see spending more than $50 keeping an outdated 26er running. I certainly wouldn’t buy a new fork for the Flash. Putting a new fork on this bike would cost more than the bike is worth. Sometimes you need to give up on an old bike and just junk it and buy a new bike. Check out these budget 29ers that sell for about $1000.
Vitus Sentier
Salsa Rangefinder/Timberjack
Rocky Mountain Growler