No, the only things you have to worry about is that the hood draws up the cooking odours or steam and that’s down to the extraction rate and width of the hood. For example, for a 90 or 100cm hobtop you can use a chimney hood of course, but you could also easily use the likes of the Elica Iceberg hood or suchlike.
There’s quite a few styles to choose from that may wel not fit with the traditional “chimney” type look.
Its a 90 width-and yes I am looking for something traditional-to match a black cooker.,or if i found it was possible for a builder to build a sort-of canopy over the cooker-something to fit in there.
Yep, you can build a canopy and, what you’re looking for in that case, is a suitable “canopy hood” which is an integrated sort of hood that has no casing as such, it just slots into a housing.