Anybody run a 400 big block with a stock bottom end?

Did it...in 1983-ish...IIRC. Well, not completely stock bottom end. I replaced the 400 crank with a 383 forged crank and rods, but ran the OEM cast piston and replacement rings. I had 67 915 heads and the block decked (again, IIRC...it was around -.010 deck height. What was CR? Who knows...

Yes, I had to mill the intake (a TM-6) to get it to fit.

With a 750 Holley, a MP (DC at the time) .509/292 cam, a B&M 10" (Super Holeshot...whoooo!) converter and 4.30's it ran 13.30's @ like...103.

Adding a glass 6-bbl hood and sealing the carb got me 13.0's @ 105-ish after playing with the jetting. It went 12.80-something after tying the frames, flipping the spring hangers, drilling some junkyard shocks for the front, etc.

Adding Centerlines (skinnies and 15x8 rears with a L60-15 McCreary dirt track tire) it went high 12.50's.

THEN we put a home made hidden bottle and plate on it. Yes, I said HOME MADE...man, was it crude...but way cheaper than buying a system. What HP? Don't have a clue, but we THINK it was around 75-80 HP, maybe...

12-teens @ 111 was the best it'd go.

I LOVED that car...beat on it, and then beat on it some more. All the while...it was my daily driver!! Young, broke and stupid...those were the days!