On a 36 Ford 21 stud flat tie-if I run an offy intake & 2 Holley 94's do I need to run a electric fuell pump?
I think you will be fine with your mechanical pump however depending how hot it gets in your area, having an electric pump to use as a back-up is a good idea. The Flathead is a great motor but the location of the fuel pump can contribute to vapor lock issues. When that happens, turning on the e-pump for a few seconds ususally resoloves it. I have one I use as a backup and it has become very handy form time to time. Also, the e-pump is good to fill your carb bowls if you haven't driven the car for several days.
Steves46 gave the right advice. I use Spectra Premium E8012S, or it's equivalent, which is a cylindrical elec fuel pump that is available at Auto Zone that lets gas freely flow through it when it is off. Use elec pump to prime carbs and to start after setting; then switch pump off. Use pump on the road only when starts to vapor lock. After a minute or so you can cut pump back off and should be fine. If mech pump fails, can use elec pump to get home. Only need a regulator if you plan to use the elec pump full time or nearly full time. Bosch makes the equivalent pump, too. I think the brand name on my last one from AZone was AirTex but can't find the box. Hope this helps, Al
Follow Steve's or Al's advice. The first time you are stuck in traffic and experience vapor lock you will wish you did.