what are some things i need to look at before i begin modify a LT1 with approximately 180k miles on it. it has new plugs, wires. and optispark. it pulls 20" of vacuum at idle, so the compression seems to be good. what do you guys think?

 

I'd say leaks, wierd vibrations, suspension bushings. Trans mount.

 

as long as its good fix the plastic stuff under the hood like sensors because heat kills them. Then go out and do a smokey burn out.

 

Just check it for leaks. It won't really start breaking until you do the mods.