[pulltilbroke]

Originally Posted by nxtruck

If you go the small block route, build a 406 ( or bigger if you can afford it ). I've ran a couple different 377s, a 383, a 421, and now a 434, and I can tell you that torque will be your friend with a 4000 lb. truck. A cast crank, 5.565 rod 406 would be a somewhat cheap build and fairly reliable for what you're wanting to do. Good machine work, ARP bolts, and TRW or similar pistons in the bottom end would be the basics needed for it to last. Keep the n2o hits around 150-200, keep the rpms around 6500-7000, and it should be pretty reliable. Your strip dominator intake would work well with something like this.
As far as your heads go, are you trying to stay with a factory-type casting? If so, try to find a pair of vortec castings. They will out-perform the 461s you have. You will have to spend some money on them, though. The intake mounting holes will have to be drilled to use your intake ( I'm assuming it's an older intake) and figure on spending some on cleaning, magging, valve job, etc. If you can swing it, you would be better off to go with an aftermarket head, such as an AFR 220, Dart Pro-1 230, or Brodix Track 1. A head like this on a 10.5:1 406 with the right solid roller cam and a 850 or 950 carb would make around 525-535 hp and do it on pump gas. If these numbers wouldn't get the timeslip that you're wanting, then you could always spray another 150 on top of it.
Just throwin' some ideas your way. My 66' Chevy LWB, weighing in right at 3950, runs 7.20s @ 94 in the 1/8 with a mild 434 sbc on pump gas, so I have a little bit of an idea of what you're wanting to do. My truck will 60' 1.50s and this is as important as anything else that was mentioned earlier. You will have to play with moving weight around, taking weight off, spring and shock selections, tires, gear, and converter to get the truck out of the hole. Making the power is just half of the story.
Good luck with it, and let us know how it goes.

I'm not really trying to stay with factory castings but I already have them and using them would keep costs down.

The intake was cast in 68 I think

Would this be a stout enough bottom end?
http://www.speedwaymotors.com/p/3176...ssemblies.html
It's part # 91510219 or would this be better

http://www.speedwaymotors.com/p/3177...ssemblies.html
part #91510280 or 91510290

Or should I just buy some pistons and use the stock bottom end?