Duals, if properly selected, and tuned; will work:

http://www.thecarburetorshop.com/Dual1barrelcarbs.htm

Triples, if properly selected, and tuned; will work:

http://www.thecarburetorshop.com/Triple1barrels.htm

Remember that the SU's are AIRVALVE carburetors!!! So even if the throttle is floored from idle, and the throttle valves are completely open; the airvalve (in this case, the slide) will open only as the engine demands. The SU's are very well suited for multiple carburetor setups because of the airvalve.

Also remember that the SU's have no accelerator pump; so proper selection and adjustment is critical to low RPM driveability.

And, if fabricating your own intake manifold: the following was posted in another thread by "panic" on these forums, and is probably the best article I have seen on intakes in the last 50 plus years:

http://victorylibrary.com/mopar/intake-tech-c.htm

You can do it for eye candy, but if you do your homework, you can actually gain a minimal amount of both power and economy. Don't do your homework, and it can go the other way!

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop