Offenhauser 2@ !bbl Holley swap info

I have a twin single Offy manifold that eventually I will play with. I ordered a pair of carbs from Langdon's Stovebolt http://www.langdonsstovebolt.com/store/#!/Carter-Weber-Carburetor/p/1222026 and will give them a try. I will need to open up the manifold so these carbs will fit. This project is low priority as my main priority is to assembly my 65 slant to go back in my wagon. It's been decked 90 thou with the head cut 10 thou; overbored 30 thou, O.S stainless steel valves, exhaust hardened seats with 340 valve springs installed after the head had some port work done to it. I had Oregon do my original cam to their 346 grind - 234/228 at .050 (which equates to 476/479 lift) - their turn time was less than 2 weeks from time I shipped it to them to when I received it back. I am using the original matching oil pump. Will be working with a set of triple SUs and might go with a set of triple Webers later. The twin Offy I'll probably be using on another slant