HR shorts are tough to come by. Do you have caps? The HR valves, especially the old ones, rely on a final seal from the cap. If the valve seeps but the cap seals it, I would just roll with it. If you dont have caps you can make medium caps work by stacking rubber washers if that makes sense. I have worked new springs over the top of old ones before and that has helped as well. Find an appropriately sized spring and thread them on over top. Then you will have more pressure on the plunger.
If you can't make those fixes work or find valves, retrofitting new valves is a bit of a project but not the end of the world. Getting new females/boots inside is unlikely without cutting the boat. If you brought it to the shop I would remove the old valve, cut a slit in the existing valve hole remove the old HR short female/boot and insert the new C-7 or D-7 female/boot piece. (The D-7 has a lower profile female and will require a smaller slit.) Then would be the time to decide whether or not the valves are where you want them. If they are, glue a donut inside and outside then install the valve. If they are not, cut a new hole for the valve, glue an inside donut to reinforce the fabric, install the valves in the new location and inside/ outside patch over the old valve location. It is time consuming but not that difficult of a repair compared to baffle work, I beams and rips in hard to work on areas. Valves are typically in easy to reach places that you can get flat and are away from seams,baffles and d rings which makes things easier to work on.