[Rick 427 Cobra]

Removing the rear spring is a MAJOR PITA. It requires removal of the interior, rear bulkhead and gas tank just for access. I had mine re arched and the result was less than I had hoped. You have to reassemble everything and drive it for a while to gauge the result.
An alternative is to fit 63-67 Corvette air shocks (Monroe #MA785). the top is a bolt on and the bottom requires only to shorten the mounting tube (saws all).
Very good for travelling with stuff in the trunk since it is variable.
Picture shows part to remove. Bolt sizes, travel and clearance is all good. Not too expensive either.