Yes as noted before,
checking the gaps for spec range is modestly easy, (need feeler gauges, and only must remove whatever needs to come off in order to get the valve covers off).
It may seem like a lot of work just to check them, but if it turns out you don't need a couple hundred dollars worth of service, you could come out ahead. I'm almost positive the lower estimate will climb before they're done with you. You want to do it right, and it's not a piddly task.
Actually adjusting gaps (requires replacing shims) seems to me like an utter pain with the cams installed (there is a special tool which hooks around the cam to depress the valve, which I don't want own ) , I bet there're a lot of pro mechanics that could screw this up, or at least hate their life during the process...
Its a much easier task, but quite a bit more preliminary work , if you remove enough parts to get the cams off between swaps (in short, the timing belt needs to come off, with all that that implies, to get the cams off).
With your admitted level of experience, it's not impossible to accomplish any of the above, but highly recommended to have the book on hand because there's some tricks and finer points that would destroy any savings if blundered.
I don't know if Haynes covers the process well, while the FSM over-complicates the picture with a giant table of shim values, when what you really need is a decent caliper / micrometer (o.oo1" is plenty accurate) and a piece of scratch paper to make notes.
The whole ideas is to replace a current shim with another of different thickness, selected to correct the off-spec gap.
I just so happen to have a stack of perfectly usable shims in the common sizes range, cheapacheapa, that will cut down on the $7-$18 stealership replacements, but you should already know which thicknesses you need before obtaining some. The junk yard has plenty also, but represents a LOT more work. It's not unreasonable to dismantle a motor that farin a self-service junkyard, just to get a little experience before tackling yours.
