First of all, if you want a T61p fan, I have them and am selling them extremely cheap and in great condition.
Second, you can use your 08/04 board, it's unknown for sure if any from that era have the improved nVidia chip, some reports are that they were slowly introduced as far back as febuary, and there seems to be a drastic reduction in nVidia failures in these GPU's after febuary 2008, which is consistant with the reports that they slowly rolled out the new design. Even if you have the less reliable GPU, you can still use the board, but I think my friend RBS was advising you that putting all that work into a system using a board that may fail would be unwise, but on the other hand, there were millions of these unreliable nVidia chips made and I beleive less then 1% have failed, and since you own the board already, why not do it? worse case you'll need a new board someday, but that could happen regardless of the system its installed in.
Third, I've never seen, nor heard of an 08/08 (or newer) nVidia board for a 4:3 T61. My guess is they don't exist, but I'd love to be proven wrong.
Also, there is no way to tell the date with certainty unless it's in the system and the serial numbers match, the board isn't dated, only the laptop, and the date on the nVidia chip itself is inconclusive.
There is also a possibility that you could find an nVidia board that was rechipped by Lenovo, which is probably your only hope of getting one with the improved GPU. I wouldn't mind finding one myself, but even the boards that are properly rechipped do fail, the process of fixing them requires extreme heat and can easily cause damage elsewhere on the board, and there are also factories in Asia that are installing counterfeit nVidia chips on these boards and flooding them on the market, so if you want a T61 with discrete graphics, you're best going with a widescreen. If you can live with the integrated graphics, then the Intel doesn't have any of these issues.
Lastly, you can do a CPU upgrade on your T60p, it will help to go with a 64bit chip, but the t60 series will still be limited to 3gb of ram, but with a 64bit OS, your apps will be able to use all 3GB, unlike most 32bit windows versions that require major tweaking to get an app to use more then 2GB.
ps. If anyone has any proof that there was ever an nVidia T61 or T61p 4:3 made in 08/08 or later, please let me know.