The v5 will only say what the importer put down as the engine number so it will only be possible to find out the original engine number from the ali vin plate in the engine bay.
I’d second this. Also worth pointing out that the L26 is exactly the same block as an L24, just with the larger stroke crank and rods as per an L28. So, you’d be swapping a P30 block, E88 head engine for another P30/E88, just with less stroke. Not worth the effort. Worth noting a great many 240Zs have L28s in them - more torque and power potential.No unless you can get the original block?