CVA used to make a Apex lineup of single shots. A few are still around. All stainless and adjustable triggers which are pretty nice actually. They were selling for around $550 very recently. Breach diameter was also a beefy 1.1". Thats larger than the T/C single shots.

I would be very interested in the new Henry though if they offered a 3-4" longer barrel 45/70 and if i knew the breach diameter was at least 1.1".

BTW it appears the Henry single shots just started shipping this month so its unlikely you will find many reviews from actual owners.