Re: 2.8 \"tricks\"
Do the air cleaner flip as suggested. A K&N air filter will help. Jack up the timing to 14 degrees BTDC (consult the manual if you don't know how to short out the diagnostic plug).
If you're handy with a hole saw, bore out the intake manifold and bolt on a Holley Big Bore TBI, or get a used GM 4.3 TBI from the wrecking yard (same size bores as the Holley). Use a base gasket for the GM 4.3 TBI as a template to lay out the holes.
The cat will help; a 2-1/2" exhaust will uncork it nicely. Magnum Roller Rockers (under $150 from Comp Cams) in the 1.6:1 ratio give more lift without changing the cam. Your valve covers are probably leaking anyway, it's a good excuse to change the gaskets while you're in there. And look at the distributor, usually it leaks oil; when it's all torn apart the distributor is real easy to get out to replace the $1 O-ring.
Hope this helps.......................ed