The ACN will work,and it's gearing is pretty good.It has a 3.67 final drive,and a .75 fifth,for lower cruising RPM.There were a bunch of similar 8V trannies that were all the same,like the the ASF,ACL,AON.
For best power and acceleration,I prefer the 3.94 final drive ratio,which was available in the ACH,AOP,AWY,AGS trannies (and a few others).The ones to look for are the ones that have the .075 fifth gear,like the AOP and AGS.