Ariens 42 inch 93604600/A 175BG42

My mower has the 17.5 hp briggs and stratton engine. I went to start it for mowing season, and it would run for about 30 to 60 seconds and emit white smoke, then immediately shut down. I gave up and went to try again the next day, only to find out, that my fuel tank was completely empty. I added more fuel, tried to start it, and I got fuel out of the exhaust. I looked into the carb and the bowl was full of gas. I pulled the plug and fuel came out when I rotated the fly wheel. I pulled the muffler and same thing, fuel in the exhaust. I drained the engine oil and it was full of fuel also.
I had a buddy rebuild my carb he said my float was stuck.
I put the carb back on added fuel, and cranked it over. The mower started and ran beautifully for all of about 5 minutes. Then it puffed large plume of smoke and some thick engine oil mixture then shut down.
Now my mower won't start at all. I can't spin the fly wheel by hand like I did before. When I crank it over, the starter just clicks and tries to spin but it won't spin. I tried to spin the head by a large socket wrench thinking maybe it was binding up. The head does spin for about 3/4 of a turn then sort of binds up even with the wrench.
I'm at a loss of what to do next. A buddy said something about being compression locked but I don't have a compression checker. Model
31C701. TYPE 0603 B1 code 09100774

And did the engine oil "puff", come out the muffler?

Sounds like it hydraulically locked up and bent the connecting rod...
 
Hydraulic as in fuel/oil got in the combustion chamber, liquid doesn't compress so something had to give when it initially cranked over...  
 
I suspect it can be repaired but your going to have to get inside the engine / pull the head, etc. 
 
Just to make sure, remove the belt from the pulley at the bottom of the crankshaft-Just to rule out something else not causing the binding (not likely).
 
Just an FYI, I had to replace a piston and head from the same engine on a Toro zero turn mower (I got for free/very locked up) about 3 years ago. It dropped a valve seat and tore up the head and piston. The tear down wasn't that bad, there's video's on-line if your mechanically inclined...  And, the Nikki carberator on it leaked internally when I initially started it (same thing yours did).  Should you repair, ditch the Nikki and put the Walbro on..
 
 
 

Thanks for the replies I hope to dig into the engine soon