Never heard of different hemispherical chambers on a CVH. Only lean burn 1.6 carb engines and 1.4 heads came with heart-shaped chambers.

Capacity might be different because of different height of the cylinder head (for different compression ratios), but they should all be the same on MK4/5/6 EFI Escorts and MK3 Fiestas XR2i and FRST.