I saw a photo of what I'm guessing is a Quax 36" modern pennyfarthing with an add-on motor in front of the front fork. (Here, second row down, far left. And do look around the site; Rideable Bicycle Replicas appear to be America's most prolific manufacturer of old-fashioned bicycles and offer plenty else besides.)
Neat idea -- but only for an expert, as "header over the front" is the standard failure mode* for a high-wheel "Ordinary" bicycle and adding even more weight up top is a recipe for instability.
Fear not; no less a personage than Sir Arthur Conan Doyle helped back the company with the answer to that problem: The Wall Autowheel a/k/a Smith Motor Wheel in the States, by either name a self-powered wheel that attaches beside the bicycle's rear wheel! I have only ever seen them on modern style "safety" bicycles, but darned if I can find a reason to not try it on an Ordinary. The added weight is all at the very back, where it'd do the most good. In fact, it's been done as recently as 1922 -- scroll almost to the very bottom of the linked "Wall Autowheel" article and there it is!
...Not that it's safe. Or especially street-legal, unless there's an exception for a 118 cc 19-teens gasoline engine. But by golly, you'd be the only one like it on the road.
* So much so that it's where the term "header" for a forward fall entered the language. Oh, and "breakneck speed," too.