1990 Ford F150 - no heat Problem

I recently replaced the fan clutch and water pump on my wife's F150.
The heat was working fine before I replaced these parts; but now there isn't any heat.

I managed to break the plastic radiator shroud pulling it off, and I don't have a replacement ordered yet. That's hopefully the project for this weekend (in addition to climbing under the truck to tighten down the radiator hose clamp - there is a slow leak).

Where should I look to solve this? The only thing I can think of would be if the radiator was still really low; when the water pump went out it sprayed a lot of coolant. I put over two gallons, which was enough to cover the fins in the radiator after letting the truck idle for a couple minutes. You need to bring the truck up to operating temperature with the radiator cap off so the thermostat opens. That might take up to 10 minutes especially if you're up north now (Brrrrrrrr!!

)The coolant level probably dropped if you didn't do that.

Also it's a good possibility the thermostat burned up when it overheated. Also make sure that the water control valve is working. Hopefully the hose is leaking and not the timing cover seal, if you have a 5.0L