The use of the sidedraught manifold & these rubber pieces assumes several things.

A. The manifold has the correct port to port spacing for the carbs which are a fixed assembly. not 4 separate carbs.
B. That the manifold angles the carbs upward at close to the original angle.
The float bowls are designed to work within a certain range of angles & it will be best to mount them as close to the original position as possible as in Aidens car.

Might be an idea to see if you can get some measurements before spending hard cash.

This is another engine from the same workshop two blocks from here & this is a LINK to another picture.
Note that the carbs are sidedraught.


Related link
Link to this photo