I'm still in the very early stages witn my 340, but to me ti seems that 500+ hp is no problem. To be honest, my engine is not stock stroke, it's got 3.35" stroke. Bought the crank used with an aluminum flywheel for 200, and have no idea of where it's from. It's an 8-bolt unit with still std size rod journals. Anyway, it's got stock length H-profile steel rods, .030 oversize Mahle flat top pistons, self made oil pan & pump & piskup setup, mech roller cam with 265/270 degrees and .440 lobe lift, bought used from moparts. The heads were also bought from moparts, a complete set of W2's and a Victor 340 W2 intake. I ported the heads, there is 1 7/8" headers, 3.5" echaust pipes and mufflers The carb is a 750 HP holley with a 2" open spacer, and the distributer is a mopar cast iron unit with MSD 6 AL. So far I haven't tuned it at all, just set the timng and idle. I have run the car succesfully only once, and I have never driven a manual hard either at the strip or street. The valve springs had only about 140 lbe seta pressure, so I llimited teh RPM to 7000. The clutch didn't work properly and the car started to crawl when the rpm got up, didn't have a two step or line lock, so the launches were pretty soft. Still the car run 10.36/132.5 at an airport against the limiter. I really don't want a stroker at the moment! The second time out, there was a good track, the clutsh worked, and now I'm looking for a spool and 35 spline axles... HJere are the three more or less succesful runs https://www.youtube.com/watch?v=sDNpATHzTN0b