318 vs 340 Questions
The OP asked if it's better to put hop up parts on a running 318 or spend the money rebuilding the 340?
He didn't say how power he's looking but I assume just a healthy ride. A 4bbl, cam kit, duals and gears can go a long way for not much money compared to a full rebuild.
And save the 340 for a rebuild down the road. And why dump a 340 for a 360 ? He's already got it. You can buy stroker 3.58" or 4" cranks fairly reasonable.