[351anyone?]

I'm new to this car thing and was just wondering if anybody could please tell how well a 351c would fit in a 89LX?

[Jarrett]

It would fit fine, the mounts and bellhousing are the same bolt patterns as the 5.0.
The balance(flywheel and balancer) are different, the exhaust is way different. Headers will be very $$$, and it will be tough to get a Cleveland to pass emissions (if that applies to you).