i have a 427 tall deck bigblock,can it be stroked

can anyone offer any advice on this matter and whatcan be done to achieve 500+hp  

yes you can, I also have a 427 tall deck that I stroked to a 496, and makes 555hp on Dart Iron Eagle heads with a 320cc intake runner, aluminum heads would give you another 50hp pretty easy. Keep in mind that you can go bigger on the cube because they have alot of cylinder wall. Summit Racing has a pretty good selection of stroker kits (eagle, scat),  You can order them balanced and that is up to you, but I had mine balanced by the machinist, just personal preference.

If this will help you more, my 1967 impala is on page 24 of the april issue in the Under Construction section and you can go through the By the Numbers section and that will give you a list of parts that I used.  

For those who don't know the history, back before aftermarket blocks, you had to use a tall deck 427--you can tell the difference by the distance between the waterpump bolt holes and the deck.  The truck 427's came with 4 ring pistons to resist detonation, hence the taller deck.

500hp is almost easy, pick your crank (Hank the Crank, SCAT, etc) and find out how much the oil pan mounting area has to be notched for it--and if the bottom of the cylinder walls need to be notched, but most likely not.  Then pick an aftermarket cylinder head and ask their tech line for what cam to go with it.