many Edelbrock, Edelbrock copies can hit 300 plus without opening the port window past what you can get by tubing them is very doable. (2.08 valve) The gains I made by relocating the pushrod over were at the most 15 cfm (330 area). So unless I see so mysterious gains at the track with the opened up port window I would never go with anything over a .350 offset. Hopefully I will find out if the delays, cost, and added work were worth the effort. I would have been racing weeks ago.