John,
What I am trying to get over, on the original plans, it calls for something similar to a knife and fork arrangement on the big end, but in this case, two conrods are offset to each side of the main rod, using full length rods with a common crank pin, whereas when you go for this arrangement, with shorter rods and pivot point distances using a king rod and plate arrangement, the angles of operation of the rods change, and has to be proved before going any further as it might require modification to other components to prevents mechanical locks.
One thing I do know, having built it, the rods on this engine are very close to the cylinder bases as they are, and as I suspect, by changing the arrangement, problems will be found.
It is OK to modify things, but only if it benefits the original design, and even then, all related components have to be made compatible with the changes made.
John