I strongly suspect that even midpriced aftermarket CNC heads will blow away any junkyard head. Be careful not to go too big and lose low lift flow, which will cost you badly on low RPM torque, in order to get slightly higher max lift flow numbers.
97 TJ Sport - 4.0/HP D30 w ARB/8.8 w LS/4.88s; 35s and flat fenders on 2.5 lift
84 CJ7; frame off restoration in progress.
The technical advice you get from me here is worth exactly what you paid me for it. Warranty issues will be reimbursed at double what you paid me for the advice.