Rebuild or replace?

[Steve French]

Hello all.

I have a 2005 Nissan Altima SE 3.5 with manual transmission.
The car has about 190k miles. I bought it used with around 145k.

First off, this thing needs a new clutch. It's still drive-able but I can tell that it's going out.
I have no idea if it has ever been replaced, so for close to 200k miles, I'm not too upset about that and I can replace it.

The bigger issue - this thing consumes oil heavily. I drive it daily and it's usually low about a quart every week. No spots on the ground when parked, no heavy leaks underneath that would cause that much loss, no power loss, no smoke or smell when started, but it's going somewhere.
I'm convinced that it is the pre-cat issue. So here's my dilemma -

Do I attempt to rebuild this thing or do I find a new (used) with lower miles and just swap it out?

Either way, I'm dumping the pre-cats so this won't happen again. And while the motor is out, I'll do the clutch.
Assuming it is the pre-cat issue, would it even be worth it to rebuild? I've found some pretty extensive rebuild kits but if there is more damage done than the rebuild kit will fix, I'd assume its not worth it.

I can do most, if not all of the work myself.

So, what do you think?
I don't have a ton of money to dump into this so keep that in mind. If I do go with a engine swap, anyone know where to buy a motor for this? Still have a bunch of places to check locally, but haven't found anyone that has one yet.

[ras_oscar]

I can't help you with your nissan, but I can tell you I have been disappointed with the one commercial rebuild motor I purchased. It only lasted 45K miles. I thought I was getting essentially a new engine. Then my Uncle the gear head set me straight. Longevity is about balance. I'm making 3000 new engines in a factory. Each piston is slightly dirrerent mass. I weigh them and select matched sets. When I rebuild, I put everything barely back to the service side of the replace spec. If the pistons are .0001in shy of repalce, they get reused. Now for me the choice would be replace the car, repair the engine, or replace the engine wth a crate motor.