A 7/8" Craftsman ½" drive full depth broach DEEP 12 point socket for removing spark plugs.
A 9/16" DEEP 12 point Craftsman, full depth broach, socket for removing Continental Motors fuel injection nozzles.
A 3/4 and a 7/8 12 point crowsfoot, the line wrench type, for loosening bottom spark plug leads in difficult to reach places between exhaust stacks.
A set of ¼ drive SNAP-ON 12 point flex sockets, and a set of locking extensions. Buy an extra 7/16" socket and be prepared to grind it real thin, to fit over the brass exhaust stack nuts on large Continentals.
A spark plug gapping tool and wire gauge set, keep your own, as people will damage, bend and totally screw up the shop's tools. These belong in your toolbox, not the shop tools.
Rivet gun, GA sheet metal is THIN, a 2X or at the most a 3X is all you will need, plus a good set of bucking bars (the ten bar set is a good place to start)
For an air drill, get a 2500-2800 RPM palm drill with a ¼" chuck, not one of those huge automotive air drills. Dotco makes a great one with a very smooth teasing trigger. I think the Sioux palm drills are OK too. IR makes (or did) a very nice one model 3AL1. Looks like the last one on Ebay was in Feb and sold for $250.
If you don't know about them, go to
www.yardstore.com and look at what they have.
Do not skimp on safety wire pliers, the cheap chinese ones will get to where they won't hold or stay locked. Get Milbars, a set of 6" and you will need a larger 9" for .041 wire for safetying props. A good mechanic needs the safety wire pliers to allow him to work faster. You most certainly can do the safety wire twisting with your fingers and duck bills, but the customer is paying to get it done, not for you to mess around with slowly twisting wire by hand. Some tight places you just about cannot get your hands to twist it anyhow.
A set of angle wrenches will be a lifetime investment. Snap On has the more desirable angles to the head than most other brands.
Ratcheting magnetic tip screwdriver also, and a tube of clover valve lapping compound to smear on the tip to make it bite tighter when you have a difficult screw.
Charles