My 215 V8 sports an
Edelbrock 500 carb (also known as a Weber and/or Carter) that has been de-tuned with smaller primary jets and rods by D&D fabrications. It's a dead bolt on and works great.
The jets used are 0.080" (original 500 uses: 0.086)
rods: 0.062 x 0.052 (original 500 uses: 0.065 x 0.052)
throttle response is great with the little 215. I assume it would be just as good on a larger 231.
RPI Engineering did a comparison of these two carbs (de-tuned Edelbrock 500 and Holley 390) on a 215 powered MG here.....
http://www.v8engines.com/old-pages/Test/carbs-1.htm
Here's pages of info on the comparison between the two carbs:
http://www.google.com/search?hl=en&q=rp ... 0+390+carb
Brand new with manual choke was like $200. They are on ebay all the time. Any parts store would have them available, too..... Advance, AutoZone, etc......
Of course, you'd have to pay a little extra for the new jets and rods to swap in
Just an idea.