they will over heat easier than you give them credit thing is you either never notise when they do or they don't damage themselves when they do. But i have seen plenty of modded 350's go to the yard cause of a bad run on a hot motor. as for punching to a 455 yes that would give great power but for the cost it is cheeper to buy a 454 and punch it to a 502.you would get the same times and a much better responding engine as well as the added reliability of a less modded motor





*edit* had to add this *edit*

http://www.themotorbookstore.com/chevy6cyl.html this is a great guid to building an i6 at any price range gave me all kinds of great ideas for mine