Don't see why not. It'd be like any other butt joint. Won't it look a bit fugly though? It'd rather ruin the clean smooth lines of the wishbone, even with most excellent welds.
Could grind a vee and fill it up with weld, grind back so it’s smooth... I’m more concerned about TIGing cast parts though. Seem to remember reading somewhere that they’ve got lots of impurities so the weld is wack.
I might be tempted to drill some holes in the tubes and do some plug welds too. If you're going to be grinding the welds smooth, will it matter if there are some impurities in the cast part?
Don't see why not. It'd be like any other butt joint. Won't it look a bit fugly though? It'd rather ruin the clean smooth lines of the wishbone, even with most excellent welds.