X heads were only 894 heads. The 915 heads were the original 360 heads, but also used on 340's starting in 1970, but machined according to application/year.
Only bad thing about 2.02" heads is that you don't know how many valve jobs they've already had. That sinks the valve & seats and reduces flow. Taking the same 915 head with 1.88" intakes and machining them for 2.02" will provide a nice, fresh, high seat and can be made more consistent through them all.
