When I ran my 340 I had fun with it until I got my ass handed to me by a mildly built 440. With a 340, Most seem to almost inevidably try and "prove" something to the BB folks and some actually do with high dollar stroker engines, but most get tired of being beat by a mild "Crusier" Big Block on the street. I gotta friend that ALWAYS tells me how he can't fathom how his little "Record holding, swingin' oil pick-up, roller valvetrained, high compression 340 gets beaten by 5.0 liter mustangs. I always have the same reply...."you gotta get past that "All motor" crap and start bombin' that 340, or you will always be behind"....
It really does kill me, and I have to laugh at the "Handling=340, Racing=440" crap flying round. Everybody knows there are WAY stiffer torsion bars to help the 440 drive right around a 340 on any day on any road course...The 440 however offers a much more broader torque band. The 340 is kinda "peaky" to me...Once you get the lighter engine components in and ON the 440, you have rotating assys today that weigh the same if not LESS than the 340. So, with all this, the 440 will come out on top, but the 340 is a good little engine as long as you know it limits.
On the other hand, if you buy into all the hype of "Them little 340's were some badass engines" your destined to run up on a Big block that will out handle you, out run you, and basically, out shine you come show day as well...I guess it really depends on how you rebuilt your 340 as to how much power it really makes and how "Satisfied" you will be with it...As stated, a 400 HP 340 will work great for a crusier...