i have a 87 monte carlo ss with the orginal 305HO V8 it has 145k on it and its time for a rebuild just wondering if stroking the 305 will produce respectable power in the 300 to 400 range or if its better just to go 383 stroker which ever is cheaper is for me any help is appreciated

While it's quite possable to "stroke" a 305.....you'ld be ahead of the game both power and $$$ wise if you build a 383.
Hell.....the cheapest route would be to drop a "crate 350" in, add a decent exhaust like either the Edelbrock TES or Hooker headers, backed by a mandrel bent system by Torque Tech or dynomax....insert the muffler brand of your liking (Flowmaster in my case). Buy a set of factory Vortec heads and matching intake and you should be comfotrably in the 300+ HPrange. And anything you buy for a 350 will remain "useable" if you later stroke it out to a 383.