I suspect you mean crankshaft, not camshaft.
No, piston orientation is of no concern on a low-tech engine like a Briggs; they don't use offset gudgeon [aka wrist or piston] pins, or pegged rings. Those do require specific orientation, and there's always a mark on the piston crown to indicate it.
It will be difficult to turn the engine over by hand, just by gripping the crankshaft end. With the flywheel fitted, it should be fairly easy, by grabbing its outer edge. A matter of leverage...
Do you have the workshop/service manual for that engine? That will give you the correct fastener torque settings, as well as valve clearances and other essential info.
If not, get the Part Number from
http://www.briggsandstratton.com/us/en/shop/parts-and-accessories/repair-manuals then do a bit of Googling - it's not hard to find free PDF downloads these days.