Haynes maintenance manual, covers the CB400F in great detail. Photography and detail very good. The Clymer manual is a good second best, however, their book seems to cover the CB350F and the words "CB400F similar" a little too often for my liking.
Clutch nut spanner, I made one from an old 7/16 Whitworth socket and a lot of filing to form the four castellations.
Wheel bearing retainer spanners, again I made mine from steel bar & bolts.
Rear suspension bush extractor/installer. Another home made device made from scaffold tubing, large washers, nuts & bolts.
Swing arm bush installer. DO NOT USE A HAMMER! these are made of a composite material and very brittle. Better to use a length of 12mm studding, long enough to pass through the swing arm tube, two steel plates suitably drilled to accommodate the studding and a 12mm nut on either end, now just wind in each bush with the two nuts one by one.
Useful bits from your household waste: An old plastic milk container with lid (filled with white spirit), old washing up bowls & microwave meal trays make excellent part washers. Old toothbrushes are great for awkward nooks and crannies.
Cleaning tasks: cotton buds and various solvents useful.
Seal removal: A claw hammer wrapped in a cloth will lever out the fork seals easily after first heating the legs to around 75°C.
I had access to: a bench grinder/polisher, lathe, pillar drill, taps & dies and bead blasting cabinet. A few helicoil inserts for damaged threads, M5, M6 & M8 were used. This helped me to keep restoration costs to a minimum?
Socket sets: For motorcycle work I find that a 3/8th's" socket set is better suited than the more conventional 1/2" type. This is especially true when buying a torque wrench, the range of torques and better feel it gives will save many a stripped thread. Sometimes a socket of the right size can be useful as a puller/pusher of various seals and bushes, worth bearing in mind.