There's a dozen or more detailed (inside and outside) pics of the CanadianNo.4(T) Long Branch chest in the MKL
.
1945 Enfield No.4 Mk1*(T) Long Branch Sniper Rifle (click here)
From the entry, go to the 160 picture photo montage and compare the chest pics against your C. No.7 chest and I think you'll have all you answers.
Personally, I don't think it's worth trying to convert.
Regards,
Badger