Have a '90 K5 and am planning a rebuild. Still has stock 350 TBI. Want more HP and TQ with the new engine. I know I could build a 350 with much more power than the stock engine. I also know I could build a 383, but I'm concerned about having all the machining done to the block, as well as reliability issues. I have heard good things about the 406. My question is, isn't the 400 an old engine? How difficult would it be to find parts? And, most importantly, are these engines reliable? If I went with a 406 could I use the Howell/Holley 670 CFM TBI unit on this engine, or would it be better to go with a multi-point system? I'd like to stick with some kind of fuel injection so I don't have to "rig" all my computer stuff to keep engine lights happy, etc.