Scoutmaster, put the intercooler in!!
I'm in process of installing one as I write this....I have a lot less room [84F250] than you, and have had to make a few mods!!

I tried methanol/water injection kit to keep the EGT's down but still ran 1000 to 1200 towing thru the steep grades.

The reason for in intercooler is simple....cooler denser air....some intercoolers are better than others but any are better than none!

I'm not a mechanic...but do not understand what an intercooler would have to do with air emissions??

 

The intercooler will lower the combustion temperature. This reduces the NOX produced. Compressing the air will heat it up. This is good from a combustion standpoint, but the hot air is not as dense as cool air therefore not as much can get into the cylinder during the intake stroke. Lowering the combustion temperature is the reason EGR is used on cars and now trucks.

 

The cooler denser air also means more oxygen in the cylinder.

More oxygen, more complete fuel burn, less black smoke and less unburned hydrocarbons in the exhaust.