Small block or big block in a truck?

Myself I'm doing a pump gas 408 for my truck. I've got a $150 brand new Speedmaster air gap intake waiting to go on, I got some brand new in the box headers on Craigslist for $80.. I've got the nicely rebuilt 596 heads that were on my Duster that were swapped out for the $700 speedmasters which is also an option for a new build... A scat rotating assembly is in the $1,500 range.. I know the 440 source rotating assembly start at 2250...
In my mind I have a big block inside a small block...