How would you rebuild this 318?

I don't think you will find a stroker kit for a 318 anywhere near $1500. With both the 340 and 360 kits you can find inexpensive ones with hypereutectic pistons and cast cranks. I have never found those hypereutectic stroker kits available for the 318. Many 318 stroker use the quality/expensive diamond piston, so the kits tend to start at $2400 and up.
Pay for the balanced kit if you decide to go that route.The forged crank is your friend to balance.