These push rods are 5/16″ diameter with .049″ wall thickness and are rated for up to 500 lbs valve spring pressure. Valve springs used in the TR6 engine are generally under 200 lbs at full open so these push rods offer more than ample strength margin. With each push rod weighing about 7 grams less than the original, I believe these push rods offer the best strength to weight ratio.
The original push rods are about 1/4″ diameter so check that these larger diameter push rods will not interfere with the head. Generally there is no interference when using original rockers or 1.55:1 ratio rockers but head castings do vary. Using 5/16″ diameter push rods with 1.65:1 ratio rockers will generally require a little grinding of the channels in the head for clearance.
Push rods are measured by “Effective Length” from the bottom of the cup to the lower end. Lengths other than those listed are available by special order.