its not strange its stupid, y8 heads are at the most 100 bucksIf the vtec system began to malfunction and you had a spare y7 head. Or if the timing belt snapped and you destroyed the valves on the y8 head. Y7 heads are much cheaper. I've seen stranger swaps.
best swap Ive seen was a gm 4.3 turbo (typhoon/cyclone) swap into a conquest