Pointing Round a window

Hi,

I have a stone house built in 1872 with single glazed (brrrr!) windows. Most of the windows have great gaps around the exterior were they meet the stone walls allowing moisture in etc. In the past I have used modern frame sealant but the gaps are fairly large, and it's not in keeping with the house. Can I just repoint around the window? Is that what would have been done originally done? What mix should I use for the repointing mortar considering its a stone built house?

Thanks

using mortar will crack where it meets the window frame! if the space is too large you can block it out with mortar and finish with this

sand mastic