Comp Cams #901 springs are a popular street replacement. Without me going back to re-read your description, was the rusty cam you took out a solid lifter cam? The lifters you are getting refaced were obviously from that cam so the pushrods can be reused. Let's talk about lifter refacing. Does the machine shop do that operation often and has the right machines to do so? The lifter faces are ground with a crown and not just machined flat. THe lifter crown and the taper on the cam lobe makes the lifter spin in the bore and prevents premature wear. A lifter with a bad crown (or no crown) won't spin and will flatten the cam lobe in a real hurry.
View attachment 1716286720