I've been building a Model Maker steam engine from solid billet (no castings). I have deviated from the blueprints by adding reversing gear to the engine. I have set up temporary adjustable valve rods to try to determine the best length. While I have equal travel of the valve...I'm finding that I'm not getting full steam port exposure with the valve moving top to bottom. I'm guessing there's really two ways to make adjustments to this..one: mill off the top and bottom of the actual valve block or two: make new eccentrics with a slightly larger throw. I'm a bit concerned with milling the valve...my thought is if I mill too much..I may not get adequate coverage of the ports during exhaust. It seems remaking eccentrics with about .060 throw might give me the port open g I'm looking for. Any thoughts or recommendations of options or concerns would be appreciated.