[JC455]

The Edelbrock rails fit fine on the Tomahawk/SpeedMaster/ProComp/etc. manifold.
They are all a copy of an SD Performance-ported Holley Street Dominator that had injector bungs added to it.
I own several versions of it- they all seem to match up the same.

Side Note: Luhn Performance made me some fuel rails for my Offy 2x4 conversion- the port spacing is the same as the E-brock's too.
His rails come in various finishes, but I like the anodized black ones I got-- and his prices were better than Amazon's price on the E-brock rails.