IMHO, the Offy 360 is one of the best manifolds you can run on a SBC. I ran one on a basically stock 400 SBC in a '62 pickup. The only changes were an earlier double roller timing chain, an old Isky 30/30 cam, a 650 Holley DP and Hedman headers. It made good low end power and peter out until around 6 grand.