'63 valiant 4 door /6 cruiser questions.

Ok unless its been rebuilt you have the early cam. a 72-74 cam will be better if you want to stay stock. If your getting a new cam anyway I would get an Erson RDP torque cam from the group buy over at .org . Just call Erson and tell them your with slant six.org an you get the special pricing. RDP is reverse dual pattern (remember the slant isnt a V8). Its an Excellent stock like cam.
As for the drain problem...its like a pick up truck drain ....a small cloged passage just doesnt get it done. I use stiff fence wire to push the debris out the bottom after I vac the big chunks out.
Frank