400 BB Mopar dyno test

Rumble:
Everything has to work together. No matter the build, if you throw things at an engine, sometimes they work great and sometimes they are crap.

Given the parts you have, I would lean towards the XE274 cam for more drivability unless you don't mind the Thumpr idle.
If you use stock size valves, not much more bowl work can be done without hurting the port...you can thin the guide boss down some and work the S/T more but gains will be small...I would max the pushrod pinch before I did more bowl work.