Chevythunder, when you mention a 4-door '67 Chevy I assumed that you were looking at doing some engine work for a family cruiser that has a little more "pop", and not a full out performance build. If you're just looking at rebuilding the engine, or even doing a little stroker kit to squeeze out a little more HP and torque for a better passing gear than I'll stick by my original advice that you take a look at GM Performance crate engines. Not everyone needs or wants a full out build, but this is NOT to say look at the wide range of engines being offered today by fly-by-night shops under the moniker "crate engine", but to look specifically at GM Performance. I would have a lot more confidence in them than the no-name shops.

If you're looking for a high performance engine, with more bells & whistles than are offered by GM Performance then I would advise you to shop around and find a quality shop that you can trust to build what you want and can show you a successful history that's not just talk. One example that I would want to see might be recent record holders or guys who've been tall in the winners circle in their chosen race venue running drive lines from the shop, or maybe hard dyno sheets showing black & white performance data for their different levels of builds. A shop that wants to dyno your engine to break it in and prove it's right before it goes out the door says a lot for me, but then I may not know, or care

Best of luck making your decision. One way or another you're looking at spending a pile of money, so giving it some thought and taking a path that you're comfortable with is the right thing to do, IMO.