Possibly, BUT, and this is a rather big BUT.... The CPU is soldered directly to the logic board. It's been that way for probably at least the last 10-20 years give or take. So you'd have to transplant the entire logic board.
The board would probably fit physically, but I personally wouldn't chance it since it's probably at least even money you'd destroy both computers. Sensor cables would probably be in different locations and not necessarily reach, the top case may not necessarily work with that specific logic board, and of course you have some high voltage backlight pins in the LVDS cable that... Well let's just say if the pins in the LVDS connector between the two model logic boards don't match EXACTLY, you'll see a big puff of gray smoke coming up from the system. Not to mention there are a lot of cables you need to keep track of, and the cable that carries the power from the left I/O board with the magsafe port in it, to the logic board, is a bit tricky to get into place.
Swapping the HDD and RAM should be doable, though getting at the HDD on these systems requires some effort, and both a PH0 and T6 Torx screwdriver that the average person usually doesn't have in their household toolbox. There are also a few fairly delicate cables you have to be aware of. It's also REALLY easy to bend the crap out of the bottom case if you don't know the trick for getting the top case off of those systems. Every single guide I've seen for taking them apart, including Apple's, tells you to do something virtually guaranteed to cause at least SOME damage to the bottom case. But it's my little trade secret how to get them off, every time, without causing any damage to the bottom case.
If you are not used to working around sensitive electronics, I would really recommend you not even attempt it. Plus, over time, with the heat generated from the CPU, the heatsink gets bonded to the bottom case, and you have to know how to deal with that and account for brittle solder joints. You don't want to flex the board and crack one of those joints causing it to go cold. Take it somewhere and have a professional do it. Since we're talking just swapping the HDD and RAM, it'd only be about an hour's labor, so in the $100 range. And if anything happens to go poof, in a small cloud of thick gray smoke, then they're on the hook to make things right.
Honestly though, with systems that old, you probably want to just get a new one. The Core 2 Duo model, IIRC, was limited to 4GB of RAM, which will probably be barely enough for Lion and apps designed for Lion which assume virtually every system comes with 4GB+ RAM. Not to mention they're going to assume a video card far beyond what's in either of those two systems. If it were me, I'd save my $30, put it towards a new system that will come loaded with Lion. Even a current gen MacBook would give those systems a good run for their money. And the smaller display would be more than made up for by the QUALITY of the LED backlit displays Apple's been using for the past 2 years or so. It's time to put those out to pasture if you want to run Lion. But I wouldn't worry too much. Snow Leopard will be supported for quite some time to come by all the major app makers, and it's a pretty solid OS. There'd be no shame in using it while you collect your pennies to get a new system.