Hob hole - changing from electric to gas hob

I currently have a cheap electric hob that I would like to change to gas hob. The gas connection will be done by a suitable gas engineer but currently shopping for gas hob. I think the hole is too big so not sure if I have to buy a large gas hob to cover space. The current electric hob surface dimension is 77 x 51 cm with the hole being 75.6 x 49.5cm. Looking at gas hobs that are 75 x 51 cm the holes required are typically 56cm x 48cm plus or minus a cm ( example...

Hob hole - changing from electric to gas hob