[carbon777]

A stock block will be fine for street use but lots of track time or over 600 hp you may split the webs. True a Dart block will give you extra insurance but even with a Dart block other things can go wrong....nothing lives forever!

One thing I will say is there is special machine work that needs to take place to clearence the block for 4.170 stroke plus you need to use a small base circle cam to keep from hitting. Your machine work on your block could run ~$600 - $700 dollars. Now if you go with a Dart block and the "same" bore and stroke you will need to machine it too. However most go with less stroke and more bore to get the rod ratio better closer to 1.54 and avoid that extra machine work.

The other thing that kills stock blocks is RPM ......keep it under 6K and it will live much longer.

I currently have a 427w.

Hope it helps.