I too have a older Richmond 5 speed (5th is 1-1) with a Hurst shifter in my Cobra. I've had it in the car for close to 25 years now. If you asked me what's the #1 thing I'd change out on the car, I'd say it's the Richmond trans. I haven't done that yet just because I drive the car frequently and my garage time is focused on 2 other car projects (home built Ferrari GTO and Lambo Miura). I really like my Cobra and now enjoy driving it more than working on it.
Shifting on the Richmond is terrible. Some of that maybe the the Hurst shifter, but some is surely the trans. I've adjusted the shifter many times to get it to "best adjustment" which still leaves a lot to be desired. I do grind the reverse gear on 5th to 4th downshifts about 10% of the time even though I have many, many years of practice.
On high RPM up shifts from 2nd to 3rd, sometimes the trans gets into a state where it's basically locked up (I think maybe in 2 gears at the same time). If I let the clutch out when in this state, rear tires are locked which tells me the trans is locked up. I don't know what it is about high RPMs that triggers this but the issue doesn't happen on lower RPM shifts. The only way to get it out of this state is to bring car to complete stop, wiggle the shifter until it goes into reverse, and that must clear the other gear engagements. It's very dangerous (and embarrassing) to have to bring your car to a complete stop in moving traffic just to clear a faulty trans issue. If anyone else has had this same issue and found a permanent fix, I'd love to hear about it.
In addition to the poor shifting, I think the trans internals are of marginal quality. I've had to replace the output shaft bushing and a couple of syncros in about 40K miles of driving. I expect a much longer life from a trans than that. My Cobra is powered by a 300HP SBF so it's not like I'm throwing a bunch of HP and torque at the trans. I now regret fixing it versus swapping it out for a different trans now.
Oh well, it's the trans I have until I have the time and energy to replace it. It works good enough to get by
I just thought I'd share my experience with others so they have some insight when thinking about using the Richmond 4+1 in their Cobra.