Glad to see you checked it out first, before trying to push fuel through it to start it up .
Good of Ranger to offer the #52 Carb.
Just be aware that you actually need a Walbro #60 or possibly #64 for a 16 K' Mag, the venturi being slightly larger.
It'll probably work ok, but you will probably find it will 'Hunt' erratically on top RPM.
Will be advisable to peg it at 3100rpm (fixed jet) with a clean/new Air Filter, it will also 'lean out' and run hotter than usual.
Depending if both your original Walbro Carb and Ranger's are the older type with adjustable Main High speed fuel mixture needles or the later Eco Non adjustable Fixed Jet types.
The early adjustable ones are worth repairing if there is no Body metal/ Venturi Corrosion, as there are quality parts fitted originally and wear rate is low.
As for your original Carb, I've seen worse and cleaned up. If you can post the Numbers off the Carb and your Engine serial number, I'll do some checking for you.
As you probably know, the white powder is Alloy corrosion where Galvanic corrosion has occurred, so there will be a lot of metal pitting there after cleaning.
If not in a vital place like a sealing face, bore hole or thread, then it may ok.
Vinegar, as Mark has mentioned, should be ok for a start, but neutralise it completely after treatment and then soak the whole Carb in a mixture of Cellulose/Acetone Thinner and Diesel (or old Redex etc) for as long as you can (remove all the plastic bits and Viton ring seals etc first).
Full, Genuine Service repair Kits are available for about £17-18.00.