That looks like a decent fork. Some of those generic forks are CrMo, others are some kind of "high tensile" steel (so named because it has a lower tensile strength than CrMo). CrMo obviously a bit nicer. I think you can probably use one with a tapered steerer in that HT but I'm not 100% sure. What I would recommend is to get the fork before tacking the frame so that you can measure it and make sure it's the the length you're expecting. That way if necessary you can tweak your design a bit to match the fork and get the head tube angle you want.