Double glazing installation query

[Fhscots]

Hi we are getting double glazing measured up soon and wondered how they will address the gaps in the brickwork behind the very old units which are currently packed out with wooden blocks. I’ve taken off the beading internally to show in the photos. This was done prob 30 plus years ago.
How would the new units be fitted in modern times? And if it’s ruffly the same would the gaps need filled with foam etc?

 

[Wayners]

Giant white trim and silicone seems to be the preferred method.
Over the wallpapering if there is any.
I fixed with foam in gap then plasterboard over on many