When you brought the crank up on the timing mark, (I hope you turned the motor in the correct direction) ...you have to make sure the cam lobes are facing the correct way before you bolt the sprockets back up... if you actually removed the cams... But yeah check the easy stuff first. you may have one or more cams 180 off ...
Make sure when you are lining up the cams on the towers, you look directly on the marks at eye level, I have seen people look at an angle and be a tooth off...
Now the dangerous part is, if the cams or crank moved out of time, and you got it put back together wrong, you might have interference with the piston and valves. This is not forgiving if you are off more than a little...
I assume you turned the motor over the correct direction several times to make sure you didn't have interference right? with the plugs still removed?
I also assume when you say, "valve job" you mean checking the lash ... "valve job" means removing the head, disassembling it, and resurfacing the valves and seats ... (at a minimum)
In the end here, all you can do is go back through the manual and make sure everything is lined-up right. Nobody here can really definitively help you diagnose it unless they are there.
Problem is, you don;t have a lot of experience with what you're doing as you said, so there is going to be a communication gap.
If you are sure you got the easy stuff covered, bring the crank up on it's mark (if you go passed, you have to go back around another revolution, you cant turn it back lol) ... and make sure your cam lobes are facing the correct way. If they are, then make sure your cam timing marks are ded-nutz at eye level. REMEMBER when you rotate the motor, it goes in ONE direction. Manual should say clockwise or counter-clockwise. If you turn it BACK to match crank marks, you could be off one or more teeth on the cams.