I Don't Like Palnuts

[Overkill-F1]

A quick question for you guys about what I should use to lock the connecting rod cap nuts in place.
This is for my '52 F1 with a C1BA/8RT Canadian built engine. The engine came with what might be called tab washers (?). They fit into the con rod cap and the tabs are bent up after torqueing the nuts to lock them in place.
On the left is one of the tab washers that was originally installed in my engine. They have been used twice, during the original build and reused by the previous owner when he rebuilt the engine and can't be reused again.
I ordered new con rod nuts and what I hoped were new tab washers, they shipped Palnuts (as shown on the right in photo).
I got info from the manufacturer of the Palnuts about the suggested torque for these nuts. I only tried 4 of them and two of them failed before I got to the suggested torque of 60 in.lb. (that's only 5 ft.lb.!) I don't trust these Palnuts to stay on the con rods or to lock the con rod nuts.
My question... is it ok to place a jam nut on each con rod nut? (I can get jam nuts locally and are a low profile nut).
Thank, Terry