I have the same set-up,(Factory),on my T.F.'55 261. My draft tube/P.C.V. valve, is plumbed into the base of the intake manifold. I did have a crankcase pressure issue with this present configuration,though. Since then,I installed a vented oil breather cap,plumbed for a P.C.V.valve. This is now routed to the air breather. The engine's been running fine,since the up-grade,and it does not leak/burn a drop of oil. As far as your carb. swap is concerned,I'd think that your fuel/air adjustment,(with a vacuum gauge),will help you achieve peak performance. The 270's (that I've seen),have similar P.C.V. set-ups.
