It's not the skirtsthat are the major issue.
You may have to grind a little off the piston pin bosses for clearance but that will help balance as 360 pistons are about 20 grams lighter than 318s, so you're getting the 318 piston to be closer to the 360 piston weight.
It's been done before. Speedomotive used to sell a cheap 349 kit that could only have used the LC cast pistons and I believe they did the cleanup on the pistons for clearance.
R.