How street able are these 340 stroker motors?

I think i'm understanding better now.

This article may shed a little light as far as your project is concerned. I'm not recommending any particular parts or brands, but the 2nd engine here (scroll down) looks very close, although you will have the 3x2 intake. You also would probably be well served to spec out a custom cam just for your application.

http://www.hughesengines.com/TechArticles/10408416strokerdynotestingsept2002.php