'There is no replacement for displacement' is a solid statement and I'm pretty sure that the guys on here that have responded will agree (I'm not trying to speak for them.) But from reading this, it is relatively obvious that several of these guys have dated themselves with their comments - which there is NOTHING wrong with.
The question you have to answer is what are your goals. All out power from a SBC? Something that's fun to drive? Something that makes people take a second look? Which of these questions is most important to you? Oh yeah, don't forget the budget question.
For me, fun to drive and making people take a second look while staying in a reasonable budget was most important. I found a 327, I am running it and I love it. It screams and sticks together. From a nostalgic perspective, I believe that a 327 is the coolest SBC out there, but that is my opinion. If you want all out power, then find a 400, stroke it to a 434 or so and you'll make my 327 look silly in terms of power and torque. The same can be said for a well built 355 or 383 and it can be done cheaper than a 400. In the end, YOU need to know what your goals are and be happy with your choice.
p.s. MouseFink - in '68 the only concerns I had was when and where my next meal came from (Mom). Love to hear old tales - keep them coming!