Actually it ran on a series of rollers, the round things in the photograph, not rails. A bit late now I expect, but Part include them in their PE sets.
NB The frame was left clear, not painted, which makes masking an easy task.
You may have found it easier to have used a vac-form replacement, there are number available.
BTW it is a Malcolm Hood, search for Malcom Hood and you are unlikely to fins what you are looking for.