OK, So do the Engines that come in the 88-90 Irocs hold up good when they have alot of miles? Say 100k+? and is it worth putting performance parts on a 350 that has alot of miles?

 

If I were in your position, I would spend the money to rebuild the engine first. By making an old engine work harder with performance parts, you are asking it to die sooner. An egine with new bearings, rings, and valve job, will be able to handle performance enhancers much better.