i'm putting together almost the same thing as you, except im less stroke and comp with a set of Victors, putting twin 76mm on my valiant, and will make WAY more power than a stock block will handle at max boost, mainly cause i like the packaging better, prob try and keep mine under 18lbs, as far as twins or a single, if you shop around a twin set up can be built cheaper! because a Big 114 or bigger will cost as much as all the other parts put together, it really comes down to how much power you want to make, an WHAT YOU REALLY WANT, im shooting for 950 and keeping it very streetable, and to all the sceptics it can and will work, wrench rat built a 355 chevy with two 67mm and it made 936rwhp with a water meth injection, it was in the April 2011 copy of Car Craft, good luck with your build.