Burrs or hit marks on the male or female splines ? At the 3/4 inch point ? Piece of grit wedged into a spline at that point ?
I would not loose sleep on it.
Some connecting rods can take a REVERSION and a hydro lock.
Without knowing the OVERLAP TIMING of the cam. You can not really play with the shiny exhaust parts.
I finally enlarged the bow area. You would need to build a plywood triangular deck piece to cover the bow foam area. Is there LOADS of molded under ALL the cross seat benches ?