That doesn't look good enough to put in an engine I would build.....however with carefully watching eBay (USA) you can find better cams now and then.  However, it might last a while if the wear hasn't worn too deeply into the hardened surface....I don't know how deep the hardening goes.  Perhaps that cam was subject to a low grade oil.

Welding cams is not for home mechanics.  After the welding and grinding the surface is induction hardened.  You can't do that at home.

https://www.youtube.com/watch?v=77wq69OGkOw

Hi guys, tanks for the response.
Nice video. Always wanted to have an induction heater

Mike, why do you call me a Klingon?I am a very sensitive soul, just a little hard on the outside.

I tried to talk the price down. But he is stubborn, he now also wants me to buy the head and the cover because they are worn together and therefore cannot be sold separately. (That is nonsense of course) I asked him for more photos and he did.
I can see that the aluminum is no longer intact. So that also says something about the condition of the bearing surfaces of the camshaft.







It seems like he's actually trying to hide the damage.  
He lives too far away to go see and measure.

I watched some videos about grinding camshafts last night and I think I will leave that to the professionals.


But I did find a nice grinding machine on the internet:
Maybe also nice for you to see. https://techduc.com/en/products/may-cong-cu-sua-chua-xe-may-1/camshaft-grinding-
machine.html

To get real; I think the investment is too big. Although I think it could be done with simpler means. But I'll let it go.  

That aliexpers cam got me motivated.
But I'm going to sit on the beach today with a nice glass of orange juice and wait for it to pass.
I'm sure a better camshaft will come along sometime and I'll jump on top of it.