OK- - - -you can use solid pushrods of the correct length, or the slightly shorter, but more easily acquired 216 pushrods by the work-around I mentioned of putting the lock nuts on the underside of the rocker arms. The website I linked can fabricate new pushrods, either by using their online order form, or maybe sending them an example to duplicate. They're located in Redmond Oregon- - - -maybe somewhere close to you? Good luck!
Jerry