Factory heads do not have replaceable valve guides. When they wear there are several things that can be done. One of them is drilling out the old guides and installing new ones, either cast iron or bronze. That is damaged. My thought is itís fine if itís going on a stock rebuild but for any performance, no. Itís going to adversely effect flow compared to the other intakes. Personally I think the early 351W are well past their prime and over rated. Theyíre living on their glory days now. The big problem with the 289/302 head is not the intake port but the exhaust port. Itís restrictive even on a 289 in stock form. The 351W Head has a bigger intake port and valve but the exhaust port is exactly the same size and shape as a 289. Despite having a bigger valve, it doesnít flow any better then a 289 exhaust. Years ago the 351W was the only option besides a 289 head. I think if someone is looking for a cheap SBF head for a little more performance either a GT40 or GT40P head with my choice the GT40P head.
I would be cautious on any head with a 2.02Ē intake other then a Trick Flow. Generally youíre going to not have clearance with the eye brow reliefs on the piston. The smaller 1.90Ē is pretty much safe.
One thing great about getting older. A life in prison sentence is less of a deterrence