"Expensive" is relative. I would guess if I was rebuilding around 1500 to 2000.
And for me a rebuild on a motor in yours condition, all the upgrades the basic upgrades that make it better than stock. Including a mild trail port and stock crank being welded, clutch, billet pump n stuff.
But you could do it for less just dont be a cheap ass about it and cut corners. You dont want to have to do it again in 2 hours after start up.