either one, im not 100% sure but i think the earlier model ls1 engines actually had a regulator that was on the rail with a return, you could go with that injector rail, personally id go with this a1000-6 aeromotive regulator, i have this for my grand prix
https://www.jegs.com/webapp/wcs/stores/servlet/product2_10001_10002_750083_-1