Burned valves are essentially caused by the valve not closing fully, and therefore not being cooled. Find out why the valve is binding (if it's an OHC engine, it's probably due to cam lobe/valve stem/tappet wear. If it's an OHV, throw in sticking lifters/pushrod wear/rocker arm wear/rocker ball wear/rocker pivot screw stretch.)
Tearing down the engine will usually help you to find the cause.
As far as books - there are some good books on general engine overhaul available (check Motorbooks, HP Publishing, Bentley Publishers, and that sort of thing) and you can also find books that are targetted toward engine families - like your "Ford Modular/Triton" engine you're looking at (the "Modular" is the passenger car version, and the "Triton" is the truck version.) I've got a few of those as well - Chrysler Small Block, Chrysler Hemi, Chevrolet Small Block, Chevrolet Inline Six, and the like.
Try out your Google-Fu using some of the names I've given you above. If you're still stuck after that, hit me backchannel and I'll give you some sources after a bit of kicking around myself.
Oh - try Summit or Jeg's for ideas - they probably carry those books themselves. If not, they'll at least carry other books, and you can get names of publishing houses from them (that would cater to the performance/engine overhaul aftermarket and hobby anyhow.)
