The short answer is that it can be done.
There are 2 big pitfalls to avoid: heat sink and battery connector.
Midway through the Core Duo revision, Apple randomly switched from 4-wall heatsink connectors to the 3-wall JST connectors. All Core 2 Duo machines use the 3-wall JST connectors on their heatsinks, so you may or may not need to replace the heat sink (depending on your specific heat sink...compare pics of parts 186010 and 186006 for clarity).
To make it more complicated, Apple randomly switched their battery connectors midway through the original Core 2 Duo versions! Some battery connectors are missing 2 pins. If your Core 2 Duo logic board is Energy Star compliant, you need a new battery connector. If it is not, you can use your Core Duo battery connector (see parts 186015 and 186042 for clarity).
Also, the Core Duo machines have airport cards with 2 cables, and the (pre-Penryn) Core 2 Duo machines have airport cards with 3 cables. Therefore, you'd need to either use your card from the Core Duo (which is a slower G card) or use a Penryn airport card.
Hope this helps!