cranks but no start B&S

2007 Troy Bilt 13AN77TG766 with B&S 17.5 OHV Itech 31C7070603 E1 I have had this machine for 2 years strong engine till it blew head gasket. I changed head gasket and ran 2 or 3 hours and blew another gasket I could wigle piston so I tore it down honed it out and replaced piston and rings, found out my head was warped so bought a new head to put on it, the shroud had broken blades so I had another engine same model but different way the shroud attached and had to use 2 bolts on flywheel to attach and they were rusted and broke off so I use flywheel off the spare engine and the armature. I tried starting it and it was hard to spin and was told it was the pressure release on the cam so I bought a new cam and put it in, set the valves at specs 4 intake 6 exhaust cranking was great but then gas was blowing out the breather that was from stuck float fixed that, checked spark and it is great got good compression cranks normal but won't start. I've been on this thing every day for 3 weeks I'm frustrated as hell if I had some dynomite I would blow the thing up. I put my hand over breather inlet and it will suck in then push air outwards in out in out is that normal I thought the carb just sucked in any help?

The valves are still open and need seeing to........

I watched a animation the valves opening and closing and checked it out and they seam to be opening and closing at the right time. I forgot about the pressure release valve being on the intake valve is why the push out at the breather until it gets running I sprayed starting fluid in spark hole didn't do jack should at least pop ya thank. looks like great spark is there a such a thing as low spark or not enough to fire the combustion I don't know as you can see

Check that the flywheel has not slipped on the shaft putting the spark out of time.

yes did that sorry I should of said in original post the key is not a sherable key on this engine I pulled bolt out anyway and checked it still in slot I turned flywheel by hand and got tdc and it matched to magnet to armature for spark, it will backfire if I set valve settings backwards through the exhaust like out of time did that by mistake but no backfire when set right so must be in time. The cylinder will be a little wet with gas cause it not firing I guess but when checking I also check spark plug for spark got it then so how can I be getting spark and it not fire up no compression? got compression did not test with tester but have to turn it over with 1/2 drive ratchet very very hard by hand so should be enough compression. Checked safety switches it wont turn over if the in use I've read a lot of threads and haven't seen one I haven't tried yet I know the cam is lined up with crank I have tore this thing apart 4 times and double or tripled checking timing dots before closing it up plus it don't backfire as if out of time I got yards to mow I don't have anymore time to jack with it if I don't get it running tomorrow I'm buying a new one geez