Correct - later spec rods are longer. You cannot use them with early spec pistons - they will ram into the cylinder head.

You need the correct, later spec pistons (Zetec Central for example) - or get some made to your spec as I have done.

Arias pistons cost about 600 quid with pins. I used Total-Seal rings and had the pistons made to fit them.

I'm using Eagle forged rods. I had Arias make the pistons so the pin fits with a perfect sliding fit to the Eagle bronze bushed little ends. From memory the little end i.d. was 19mm.

I used King bearings in the build.

My pistons are 13cc dished. I have no issues with valve clearance on a standard EFI cam and 45mm intake valves.