1969 HO 350 with small-chamber, large valve #48 heads and the 744 cam. Not a common combination, but they did make a few.

I see SD421 stuff for sale once in a while. It's not cheap. I would say it falls into the "mostly-not-available" category, along with Ram Air 4 and 5 stuff. For the right price, I think you can find almost anything.

This has been "discussed" too many times to have one simple answer. You will find as many opinions as combinations. There's one thought that is universal: On the street, bigger is always better.

Start with the biggest engine you can, build it to last (but don't go crazy) using the "best" stock and aftermarket parts you can. Build it to run on 91 octane pump gas with 10% methanol like we have here in L.A. Use large valve heads but don't go crazy porting them. Have a professional set up your springs based on your cam profile. Use a cam with 215 to 230 degrees duration, or longer duration with Rhoads lifters. Use 1.65 rockers but make sure the push rod holes can handle them. Make sure the crank has all the oil passages enlarged and chamfered. Heat treat your rods, re-size them and use ARP bolts. Make sure your block is prepped by a very, very good shop. I could go on and on, but I think you get the point and everyone else fell asleep already.

I am starting to put together a 421/428(440). It has all that and more. It's going to be WAY overbuilt for street driving. That's just how I do things. But, I plan one day to turn some laps on a road racing course with the car, so I'm taking no chances.

I could honestly talk for hours about how I set-up and build my motors. Plus I'd love to wax philosophic about what combinations I'd love to try if I was a gazillionaire with nothing but time and money to spend. The engineers at Pontiac in the late 60's knew what they were doing. There's no reason to re-invent their wheel, except to take into account that they could get way better gas at the pump than we can.

Sorry for the long post. I forgot where I was.

Q

Edit: Dangit! I knew I should have checked my numbers! The 068 cam is the cam in the 350 HO, not the 744! My bad.