I know you asked for "real" driving experiences, but I'm offering this from the perspective of the owner of a moderately built up 3.4.
The 3.4 pushrod is a noticeable, but modest, increase over the 2.8.
If you throw some money at it (cam, head and intake porting, trueleo intake and headers) you can make it nicely quick.
The right combination of parts may get you around 210 or so at the crank. (Oreif has built two of them.)
A 3800 SC II starts out at ~230-240 at the crank and can be built on out from there. Lots of bolt ons available.
Would be my choice.
Will probably be my next
88 4.9 Formula IMSA Fasback..........................88 3.4 coupe -soon to be something other than red
Read Nealz Nuze! Praise the Lowered!