Honda VT250FD Timing Chain?

My Dad has a 1984 VT250FD (Eng and Frame # of MC 08). He has replaced the timing chain but it appears to be tight and can only get slow turnover with the plugs removed. We have heard that this model may have different spec of timing etc dependent on whether it is imported or not.

Does anyone know of any differing specs for this model?

Any help would be appreciated

Cheers