I don’t know if Don Young revised it, but K.N. Harris certainly did.

From examining the drawings I have:

This was with internal Stephenson’s Link Motion and for both inside and outside cylinders.

LBSC, the original designer of the model, shows similar practice as on his Juliet design, by suspending each cylinder’s valve-gear unsymmetrically from a single link swinging on a  fixed pin: a fundamentally weak idea. Harris gave the die-block spindle a sizeable trunk-guide instead.

LBSC also designed a more robust Joy Valve-Gear arrangement for the inside-cylinder version. This was the version chosen by whoever built my own society’s Maid of Kent*. 

On the other hand, the internal Stephenson’s Link Motion on our 7-1/4″ gauge version of Juliet, simply scaled from LBSC’s drawings, did not last long due to its weak, unsymmetrical suspension method encouraging heavy wear in its pin joints. (It was successfully rebuilt, with massive trunk-guides, rather as Harris shows.)

So of those three, I would choose either the Harris-revised Stephenson’s Link Motion or the LBSC-designed Joy Valve Gear. I don’t recall the latter as on our locomotive ever giving problems, but I do not know what if any design modifications had been made by its builder(s) – some years before I joined the club.

If anyone does know of a Don Young or other designer’s revision, I would be as interested as Wireman to know of it.

Rather oddly, LBSC or the M.A.P. publishers placed the details for the Stephenson’s Motion feed-pump on the Joy Gear sheet; and the latter locomotive’s pump on another sheet still!  It was antics like that which helped gain the older, published plan-sets generally a poor reputation.

+++++

*Which, christened Maid of Athens, bizarrely became “lost” some years later! I do hope “she” is still in action, somewhere.