crossram
They won't fit an a-body without surgery.
They're called long rams and there were two versions. They are physically the same size, but are called long and short due to the length of the runner divider. The longs are made for peak torque at a lower rpm than the shorts.
The shorts made their first appearance on a special run of seven 1960 300-Fs with 400hp 413s and a French-built Pont-A-Mousson four speed manual transmission. The seven cars were built for the 1960 Daytona Speed Weeks. Andy Granatelli supercharged his. One more 300-F was built with this setup, a convertible.
They are expensive, have low speed puddling issues, but when right are awesome.