There is currently a Ruger American left hand stainless compact on Gunbroker in 243. Super gun! I had one just like it. The stainless versions in the American line are all discontinued, and the lefty stainless versions were a short term distributor exclusive several years ago.
As a lefty I'd for sure recommend a true left hand action.
Is the length of pull correct on the Ruger compact for him?
Nice thing about the Ruger is, you can eventually put a full length stock on the compact rifle. Simple 2 minute swap.

A few things you could do on the Ruger to reduce recoil-

Limbsaver Airtech pad. They make one for the compact American, and one for the full size stock. Simple two screws, and with no fitting required.

How is the weight? If he wouldn't mind a pound or so extra, that is easy, and would soak up a lot of recoil.
The forend cavities under the barrel can be filled in, with anything from black silicone caulk to bedding compound.
Also, the butt cavity can be filled- anything from spray foam to silicone.

I did silicone in the butt and forend of a Ruger American Ranch 450, and it gained about 1# 4 oz., while balancing very nicely.

But, I really wouldn't do anything to that one if it is going to be his primary gun. Trade for the same one in left hand, either 243 or 7mm-08, and then modify from there if needed.

Last edited by KenMi; 10/30/18.