1- larger injectors won't do you any good unless you do something with the computer. the computer will simply adjust the pulse width to delivery the same amount of fuel you were getting before.
2- depending which header style you have it may crack. if its a one piece design with no flex joints, it WILL crack very soon. then you'll need a new header, which will then crack. a 2000+ stock manifold is the best bet here.
3- for head upgrades, your best bang for your buck will be roller rockers, heavy duty valve springs and a Hesco cam
4- you could also go with a completely new performance Golen/Alabama head or an aluminum Hesco head. the aluminum head would allow you to run about 9.5:1 on 87 octane, but you'd need to dyno tune.
4- at 10:1 you'll need 100 octane or so. 10:1 would be go for running E-85 exclusively. for 87 octane you need to stay at 8.8:1 compression with a cast iron head.
5- for larger injectors, head or cam work, a supercharger or compression ratio changes, you'll need to dyno tune to ensure adequate a/f ratios.
PM "Robert J. yates", he has done the Hesco aluminum head, Hesco cam, roller rockers and heavy duty valve springs + dyno tuning with a Unichip piggyback. hes got all sorts of info