a) The rules declare only a ‘maximum’ distance of the inner shroud tangs aft of the main shroud tangs. As as long as your inners are no further aft than this measurement, your boat is legal.
b) The F19’s are deemed legal as long as their inner tangs are aft of the main shroud tangs.
c) You can move your inners further forward if you wish.
d) The job will not cost much as no structural work is required; simply fit a sturdy bar on the horizontal plain between your existing inner tangs and main tangs. Drill a fixing hole along its length (at your desired position) and take the inner shroud to this position. As long as it’s aft of the main shroud, it’s legal.
e) There are 2 schools of thought: if one has disconnected the baby forestay found on older Hunters, it makes sense to ‘correct’ the geometry of the rig by moving the inners forward. This is because if they are too tight, they may induce mast inversion when set too far aft. Others believe they should not create a problem in light to medium airs and in fact are required in the aft position to hold the stick up when on a run.
The choice, therefore, is up to the individual.