What mods for my 904 when using the BPE 408?

For all.
Trans i recommend(same 30 month warranty as the engine)
MOPAR SB 727 PACKAGE | 3 SPEED AUTO KIT FOR SB MOPAR | 2200-2600 STALL CONVERTER

Damper I recommend (magnum weight)
Mopar Small Block Harmonic Balancer | 273 | 318 | 340 | 360 | 408 |

And a LA 360 flexplate, assuming you have an aftermarket, non weighted, converter.

We DO sell complete engine/trans packages
And we can work together on options

BLUEPRINT ENGINES BUILDER SERIES Mopar 408CI Stroker Crate Engine and 727 Auto Transmission | Small Block Chrysler | Roller Cam | Polished Front Accessory Drive