Replacing a head gasket - 86 Familia

[Liable]

Hey, I'm at the stage where I'm trying to put everything back together, but I've hit a snag being the chain to the camshaft, suddenly it's too tight for the camshaft to sit where it's supposed to. I was wondering if anyone else has had this problem, and what the solution might be short of a qualified mechanic

Any help here is much appreciated!

Thanks