The easiest way is out through the cockpit.
1964 Spitfire4 Mk1
From: Nathan Coraor <email@example.com>
To: Triumphs Digest <firstname.lastname@example.org>
Date: Saturday, April 04, 1998 5:29 PM
Subject: Replacing Spit Clutch
>My Dad and I are replacing the clutch on his '80 Spit and were wondering
>which way to take out the gearbox assembaly... up (through the cockpit)
>or down (out the bottom). Looks like it will go out better up, but
>we're not sure.