What your basically asking is exactly the description of the Canadian 12v cyl. head. Here in Canada, we did get the 12v CVCC head in 1984 but in 85/86/87 the CVCC design was eliminated and the 4th valve chamber was filled in. The Canadian head is sought after by American tuners because of this and it make 2 or 3 more HP (not sure of the exact numbers).

R2 indicates that this might be IT illegal and therefor the Canadian head may be illegal too. It's funny because I know of some Canadian IT CRX's that used to race south of the border without issue.