408 cam / build help.

Block to use?
Simple!
The one that sonic checks the thickest!!!!!!!
“Some porting?”
Are you going w/a 2.02 valve? Touch the entire port. Widen it as much as possible. An engine of that size wants to breathe better than an OE head delivers.
A cam that will make 350 HP and use 3.55 gears? Well, that may depend on how well your heads flow. The above cam is good. If your heads move some decent air, you can step down to a [email protected] or less and make that power easy! Between the cubes and decent head air flow, you’ll do it EZ!

I have seen stock headed 360 engines make that power and more with a stock 340 cam and headers. (FWIW, Also coupled with a rpm and a 750.)

I’m using a Hydraulic roller at 224@050 in a 360 with tti headers and well ported heads. A great street cam that’ll deliver good hp for sure. OH! It’s a 904/2500 stall w/3.55’s on 26 inch tires. 67 Cuda.

You got this!
Thanks for the input I will keep that in mind and will get my blocks sonic tested.