As an aside topic, would you recommend using some plain nuts when using Plastigauge to check bearing clearances?
I think this is why the supplier of the new steel capped A65 rods sell them with plain and lock nuts. You can measure bolt stretch or plastigauge with the plain nuts without destroying the locking nuts deformed thread.
Nick, a friendly warning, I would not use those nuts! I had this exact same condition when I rebuilt my Spitfire about 3 years ago. I thought to reuse the conrod bolts but wanted new nuts. I bought what was carried by Rabers for the job, they looked exactly like the nuts in your picture. It is clear from your picture that the nuts do not thread down on the bolts near far enough. They don't even begin to enter the locking portion of the thread. This was the same issue I encountered. I think you will run the high risk of them coming undone at a most inopportune time. I reused the old nuts with locktite. Has been fine ever since. Fullminator.
Thank you Fullminator for the concern. In the photo, I have not yet tightened the nuts down as I was unsure of their orientation. (Thanks DMadigan) I have since torqued them and measured proper stretch on the bolts. I had no issues. You must have had some defective nuts or bolts. It happens.