Never used seafoam, but...
For redlining a 7M-GE... Why not? I used to pull my 7M-GE to redline on a regular basis. I did right up until the day it blew a coolant bypass hose, and I swapped int he 7M-GTE. Last heard, the guy who bought it from me found no problems in the bottom end, and it had over 450,000 kms on it. The engine didn't even need to be bored, just a hone and new rings. (And valve stem seals, since they were seriously crunchy.) Even the head gasket survived, since up to that point, the cooling system was well maintained.
The problem is that it would be difficult, if not impossible to get a mechanic to say for absolute certain that use of seafoam in a 20+ year old block was the cause of failure. It doesn't help if the block was rebuilt, because it's far more likely that improper work during the rebuilt is at fault than the one-time use of a product like that.
OMG. I always thought that this stuff never touched the oil, that it was intake and maybe fuel tank only. Saw the 1/3 through PCV/Vacuum, 1/3 in the oil and 1/3 in the gas tank recommendation. I would never... but then I've always felt that the companies who produce motor oils hire some pretty good chemical engineers to determine what they put in there, and that it's not the same additive package in different product lines, let alone different brands. Therefore anything that "works with all motor oils" has to be making some broad assumptions about those additive packages, or had better be planning to drain immediately.
Edit: Oh, and guys... For what it's worth, a 7M-GTE running to redline (Which most of those who own one will do) is under a lot more stress than a 7M-GE at redline. Higher effective compression, more power, and it's going through exactly the same crankshaft and connecting rods. So... If you don't think that a 200k 7M-GE should be run to the red line... What do you think that a GTE should be run to?