I've got an old 440 fan I've collected the parts to overbore and rebuild (burned down a piston and the cylinder is too far gone to hone and go); unfortunately, I haven't had time to get going on it. I just picked up the "OEM replacement type" pistons from MFGSupply – I've heard they're the same manufacturer as brands like SPI – and a Winderosa gasket set. Total parts cost was less than $100, and depending on who you ask, that may be a better way to go than Wiseco. No personal experience with Wiseco, but what I gather is that they're a lot more finicky: get the clearances too tight or ride without enough warmup and they'll seize. Not the piston's fault, really.
By the way, I'm assuming you cleaned the crown of the piston? Reason I ask is because you should be seeing a thin layer of carbon covering the middle 2/3 of it. I'd think if that's how it looked when you took the head off, you've been running way rich.
