crew cab engine (454 problems)

[playinsafe44]

I just picked up a '74 c-20 CC SRW for a very good price, but the engine has some issues.... It has a 454/TH400 setup, unilite distributor, edelbrock carb and intake, headers with new exhaust all the way back, electric fuel pump, eletric fan, and dual batteries, power steering, "better alternator" (seller said it was upgraded), and power brakes.

The problem is that it has a knock. Its easy to hear at idle, but due to the exhaust, it isn't so noticable when revved (you can still hear it if you listen for it).

Now my question is, how should I handle this? I have a good 350 with some bolt on goodies but I don't want this to be too underpowered. I have never worked on a big block, but I sounds like it has a rod knock. I don't think I want to do a full blown rebuild on it (again, not sure what type of engine I want), but I want to get this thing fixed as cost effectively/and as quickly as I can to be able to use it. Has anyone tried just swapping out bad rod bearings?