Hi. I have made an error measuring my for a replacement window. It has come and it is 10 cm too tall. I don't fancy paying out for another window. So I was thinking about cutting part of the sandstone sill to fit the window in. Sill is 13 cm high. I considered taking 5 or 6 cm of sill and may be 4 or 5cm off of the sandstone lintel. Lintel is 25 cm high with a span of 74cm. Any ideas on this proposal. Or would it weaken the lintel too much. Window is on gable end at back and is only supporting the few bricks above it along with the roof androof purlin. Any advise welcome.