Man, thats about as basic as it gets, but the blow through like this is frought with potential problems.
If the throttle shaft is worn, it blows fuel & air out into the engine bay. The gaskets were not designed for boost & will very likely leak after a while, depending on how much boost is used, & finally, the carb needs a solid float, ... & a rising rate reg with a high pressure pump will be a good idea.

Personally, when you remember that the heading here is "Cheapest Turbo setup" I think that the simple suck through design is the go. Use a tried & true SU from the Trading Post or other second hand source.
Forget the intercooler as they cost money & defeat the budget-build criteria. Mount the turbo on a J pipe & keep the boost down so as to avoid high inlet temps which leads to detonation & ruined engines. Now that just plain defeats the whole budget concept.

Simple fact is that a very tuneable 1-1/2" SU in front of a modest sized & inexpensive turbo pushing only 5 to 7 psi into a stock 1200 will still impress as the little carb is seeing a constant airflow & not a pulse flow, so it will still perform well & is cheap as chips since nobody really wants them anymore. No carb mods required, no high pressure pump, no fuel regulator, ..... bloody perfect.

If the car is not outright abused, even the humble H145 diff can survive if reasonably narrow tyres are used.
Remember that lowest price is the only stated criteria here, not blinding performance.