No contest - buy a used 4.6 out of a wrecked Hwy Patrol Car and swap it in.

Those engines are not in high demand and you can still get a fair deal on one.

Be picky -

 

Are they typically identified as a cop/patrol engine (when listed at Junk yards) ?

do you know if/what pcm issues (or what additional parts needed) there may be if swapped into f150 ?

 

One dead hole on a 4.6 might not be a death sentence. Could be a bent or stuck valve sticking open. Bottom line, find out why the cylinder is down on compression or not firing and go from there.

 

Doesn't have to be a Hwy Patrol Car...
..
As for Hwy Patrol Car engines... There are no differences (except the addition of an oil cooler) between them and the civilian models; any performance enhancements came from a dual exhaust (which was a HPP (Handling Performance Package) option on the civilian Crowm Victoria and Mercury Marquis), and in 2004 a more better airbox with a larger MAF (80mm). *Using the Hwy Patrol Car airbox+MAF would require a tune to change the MAF table.

Not so for the owners of the discontinued Crown Victoria / Mercury Marquis looking for obsolete parts (especially the intake manifolds) since aftermarket offerings a very poor quality..
.

 

I just looked at FB marketplace, and on the first page is a low mileage engine.

 

3V.

 

Yes - I forgot about the 3 valve - those will be a lot harder to find.

 

Swap it yourself! (If you have the Equipment). Your truck looks clean. I'd probably see if I can get to root cause and then fix it.

 

The 4.6 motors did last a long time--as can be seen in the available engine listings in Car-Parts.com. Many have very high miles.

But a regular mile 4.6 engine should run $1500 to $2000.

You can buy a remanufactured 4.6 engine from Summit Racing for $3.5K.