Install the main timing chain in order to turn it over

A similar question was asked on your site it almost answers my question but not quite. I am doing an engine swap the new engine had a hole in the rear timing case cover XML add a week to the build had to swap it out with the blown engine's rear timing case cover once the new one was installed and I got the cam chains on. I had to rotate the crank over by hand to land on the compression stroke and find TDC, but it will not allow me to rotate a full 360° because the piston sounds like it is hitting the valve on the front middle cylinder the answer to. The other question said to install the main timing chain in order to turn it over, but I need to get the TDC in order to install the chain to turn it over I only turned it over by hand so I know the valve is not damaged. I am able to get to TDC if I could figure out why the engine will not turn a full rotation. Any information would be appreciated.