Rebuilt 340 really difficult to turn over

Thanks guys looks like I probably screwed up big time. Had a bag over the engine most of the time but the last month or so I left it off because I had all the accessories hooked up and it wouldn't fit. Didn't have the spark plugs in either so it's probably rusted. I'm just going to take it back to the machine shop because I can pretty much guarantee I'll screw it up if I try and mess with it myself.