The gun should work just fine with out the Curtis latch. It, just like the roller latch, was in addition to the regular J spring latch, but the Curtis latch was only used on guns without ejectors. Without the Curtis latch, the j spring should hold the fore end as well as any other gun made before or after the 1913-1919 period when the
Curtis latch was used.
If you want to make, or have made for you, a new spring lock for the Curtis latch, the drawing is found on page 160 of Brophy's "Plans and Specifications - LC Smith Shotgun". The spring latch is made from 0.042" thick spring steel. Brownells used to carry annealed spring stock which could be formed and tempered for the latch without much problem.