Has anyone done this conversion? I believe it to be quite simple, requiring only a change of sear. The idea being that the bolt opening cams the striker quite a distance plus the bolt itself cams the striker so the combine travel should be sufficient to fir the cartridge but it might require a stronger firing pin spring.

The conversion fof the 1917(pattern 14)
works just that way. They are not too good
the firing pid drop is short, and when you
add a strong spring it gets harder to operate.

I managed to fire a Lee Enfield by depressing the trigger and closing the action quickly. It does have a heavy striker. That's where I got the idea from.

That is a solution to a non-existent problem; cock on closing is designed that way for a reason; to be able to open the bolt with less force than if you have to cock at the same time. And, some/most/maybe all cock on opening conversions make the striker fall less, and might result in mis-fires. No need to do it.