Will leave the fuel pump question to others.
If you have the CORRECT size Stromberg 2-barrel with the correct 2-barrel intake manifold, a carburetor designed for a 302 would be preferable to one designed for a 270.
Stromberg made hundreds of different 2-barrel carburetors.
The Stromberg type WW has one design flaw that should be addressed. Stromberg used an aluminum throttle body on the type WW carburetors. The aluminum, over time, oxidizes, and "sandpapers" both itself and the throttle shaft where the throttle shaft goes through the throttle body.
Design fit was 0.004~0.006 inch.
Bushings, professionally installed, will cure the issue.
Once the throttle body issue is addressed, the WW is virtually bullet-proof.
Jon.
