Variable length intake manifold

Forgive me asking so many questions. The restoration of the Octy continues, not only on the body but also mechanically. 

I found I have an oil leak from the rocker cover. To reach it, I had to dismantle the whole intake manifold. I found that the internal flap that change the "length mode" has been removed probably because of cracking. Furthermore, the diaphragm that moves the flap has been busted. So, now I have a manifold that is always in the short and wide path (actually, it drives the air through both ways, long and narrow - short and wide). If my understanding is correct, this mode is when the engine operates at high rpm. Is there any serious impact I left it this way? The engine is running very steady, it accelerates very good and no lights on the dash. 

The only solution is to buy a new manifold. But they are quite expensive and it would justify the expense if only there is any big problem if I leave it as it is now. 

Thanks!