This information is from the Cyclopedia, it is very clear that the location is at 123 Johnston Street, but today there is no such house at this location.
“David Ballingall, engineer, 123 Johnston Street, Fitzroy, was born in Edinburgh, Scotland, in it the year 1845. Arriving in Victoria in 1855, at the termination of his school days, he served an apprenticeship of five years to the engineering trade, and in 1887 started in business on his own account. He makes a speciality of boot manufacturing machinery, and is ably assisted in the business by his son, Mr D. E. Ballingall who entered his father’s workshop at the age of thirteen and as a student at the Working Men’s College, Melbourne has gone through all the branches of the engineering course. Mr Ballingall is the patentee (under Royal letters patient) of a lasting and heeling jack for good-year and all welted work, which is used by all boot manufacturers throughout the Australasian States, and is remarkable for its superiority over all the other contrivances of a similar kind. Although simple in design, it is almost ingenious appliance, and can be easily worked. Mr. Ballingall belongs to the old school of engineering in which the word ‘shoddy’ was unknown. As a finished master of his craft, his work may be relied upon to be of the very best.” (The Cyclopedia of Victoria, 1903-1905, Vol 1, p. 584)