Just getting set to modify my 454 for a torquey street monster. Here's what I've got: Comp Cams XE268 K-kit (lifter, 911 springs, seals, retainers, locks, etc.) Comp Cams exhaust rotator elminators Performer Intake (no EGR) Dynomax headers (1-5/8 primary) GM steel shim head gaskets (.020 compressed - trying to bump up a little compression) Stock (as far as I know) '75 454 truck motor with 781 heads. I just took off the intake last night and this motor looks very clean inside. Still waiting to get the heads off, but am contemplating what head work to do. I'm not planning to touch the bottom end unless I find any big surprises. Should I just use the heads as is? Plug in 2.19/1.88 valves? Do some port work/bowl blends? Or something else? Any idea what this work would cost from a "good" shop? And what should I be asking when I start calling machine shops? With the combo I'm building will the big valves really help much? I've also heard that these heads are a lot more prone to cracking once you put the big valves in them too? I still don't know if the valve guides are sloppy or not since I don't have the heads off, and I don't know if the stock spring pockets are going to fit my 1.55" springs and rotator eliminators. So I might end up taking them to the machine shop anyway... Let me know your thoughts? Also wondering what oil and/or additives are best recommended for breaking in a new cam - especially since I've been hearing some buzz about oils not having zinc(?) in them anymore that kills flat tappet cams? Thanks.