This 50 pin header has the same spacing as the NEM651 NMRA small 6-pin connector.
In fact, we make the NEM651 connectors we sell from them. We use them to make custom connectors – you know, that 7 pin connector you need to go from your tender to your loco! We decided that our customers should have the option to do so themselves.
When you cut the plastic header you will loose at least one pin – sorry.