my e36 m3 3.0 was run up recently in 5th on rollers and did 317 bhp with 345 nm torque.
mine had some porting of the head,hand built free flowing exhaust/manifold and good incudction kit and chip.
but my car is a track car stripped out-used to piss all over all other e36 m3's on track though on both corners and straights-until the bottom end let go!

your flyheel figure seems high,but who knows?
ive just sold an evo 3.2 that did 320bhp on rollers with a remap-rest was standard.