Does any family member know her actual birthday as opposed to just the year?
I hate to say it, but it's even possible her parents were not married (even if she thought they were). It seems to be a common anomaly in Scotland that children born illegitimately, who knew who their fathers were, would grow up with his surname rather than their mothers. I realise I am not helping but thought you should keep this in mind.
On a more positive note, I have found a George McLeod who was a Boilermakers apprentice in 1901. He was actually born in Glasgow as George Findlay McLeod on 4/3/1882, son of Walter McLeod (also a boilermaker who was deceased between 1891 and 1901). Discovered that this George McLeod joined the Royal Navy on 18/9/1902 for 12 years. Had to smile as he was then 20 years old but shown as 'Rivet Boy'! The record shows the ships he sailed on, and when, the last entry being on the 'Algerine' from 9 June 1911 to 20 Nov. 1911 - cannot read the first word of the last part - 'something' Run San Diego. His rank at that time was 'Leading Stoker'.
Don't know his whereabouts after then or if he died on that last run. Being in the navy he'd have travelled all over the world and no doubt into ports in the North of Scotland too.
In 1901 although there were many McLeods in the Highlands there were none that were Boilermakers. Indeed, the majority were in Lanarkshire. Perhaps it was Margaret who was from the Highlands although I can't find many Malone's in that part of the country.
Having found just one George McLeod in 1901 who was a Boilermaker (albeit apprentice then), and earlier census showed his father was also a boilermaker, it seemed worthwhile pursing him, as it were. His birth date was 4/3/1882 in Glasgow and this birthdate/place concurs with the naval record. So, could this be your man perhaps and, if so, where/when did he meet and take up with Margaret Malone and where was Jane born?
Annette