It would normally be at least 35 crankshaft degrees past bottom dead center before the inlet valve was completely closed, so that is not a very convenient way to check the camshaft timing. Can you find the crankshaft position, near TDC, where both valves are open the same amount? That is a more useful way to check whether the timing is wrong.
Did you lap the inlet valve? If it was leaking it will have needed lapping. Most Honda mower engines have a decompressor, and this makes it more difficult to tell what is going on with compression. You have to check the tappet clearances in the right place rotationally, or you will get misleading answers. You now have more compression, and that is good if the inlet valve was leaking, but if you have adjusted the tappet clearance with the camshaft in the wrong position, you may have simply disabled the decompressor.
If it now has good compression but fires through the carburetor, either the inlet valve is still leaking or the ignition timing is seriously wrong. You can probably check the ignition timing roughly by holding the spark plug lead in one hand and rotating the flywheel with the other. When you feel the pain, note where the flywheel is. Start off turning it slowly of course - you'll soon find how fast to flick it to feel it without spoiling your day.
