Clutch/brake boot is a rare item, can't help you there.
The gear lever has a boot (LV9/BOE/FV17601) with a large (lower) and small (upper) hose clamps. There is also a canvas dust cover that goes around both levers, see pic.
Roy Elvis did have some gear lever boots :
http://www.champ-sparesukltd.com/
Re. your pics.
Had a quick look at the rifle brkt upper, divers side. It is longer than the pass. side, and runs towards the rear, with the rifle leaning back at an angle to help in egress/exit. The pass. side is shorter due to the mounting of the spare wheel.
The water jacket cover's are prone to corrosion, well spotted. There are three of them and are probably all worth replacing. I have ,made them out of Stainless and Brass.
The rectangular cover block on the back of the head, ditto.
The block with all the pipes on the back of the block ditto. These are breather pipes for dissy etc. and no doubt full of crud. The blocks are available NOS.
Wait till it hits 45, all the grease will run out, hey presto, job done!
Rich.