454 in a '79 K20

[zac]

As I do test drives as I work through all my problems, I'm noticing the 350 is not really cutting it. I can't imagine I will be happy when I'm pulling a trailer or have a heavy load in back. The truck originally had a 400 sb, but it's long gone. I have several 350 4-bolt blocks I could do a 383 kit in. And I have a good '74 454. So I could approach diesel torque, with half the mileage. But I think I will only put 3000-4000 miles a year on this thing, anyway. Did 73-87 4x4's come with big blocks? By the looks of it, you would have to do the dented firewall trick like on 67-72's. Anybody done this? My truck has a th400 and np203. Thanks