94 won't start

I need some major help.
I just put a new, but used 4.0 v6 in my explorer. I used everything from the original motor except the block and the heads. I bought it not running because the engine was siezed up. We finally got everything put together and got the engine installed. Everything seems normal, except it won't start. I have spark at the plugs, I have great gas pressure. I have a mechanic friend from a ford dealership and he has looked at everything for me and used his big diagnostic computer thing and everthing checks out fine. The only thing we can think it might be is the camshaft sensor. It is the one that has the clear window on the top to adjust it. If anyone has a suggestion. I would be much abliged.

Finally figured it out. When I re did the engine, I used the old fuel rail on the new block I put in the truck and the fuel injectors wouldn't work with it. So after an hour or so of replacing injectors, it fired right up.