Replacing window in masonry

[Martik]

1a, 2a

Existing window is framed in 2x4 wall with 1x6 'framing' and 2x2 trim on the outside. I want to replace it with a picture Vinyl but since the sill (stone) is higher than the frame I'm thinking I may have to leave the 1x6's in place and order a window 1/2" less than the width and height then cut off the flange. Question is, how do I securely attach it to the building or is there another approach?

[Art]

The right approach is to have a mason come in and remove some stone, install the window per installation instructions (visit Pella's site for example) and then replace the stone by the mason.

Anything else is a waste of money.