Around the beginning of the year, sometime after Christmas, I will be aquiring a 390 FE and a top loader 3 speed, all I have to do is pull it, free of charge. What kind of performance is the 390 capable of? I'm looking at an F100 shop truck build, can the 390 be a mean street performer? I'm wanting upwards of 800 horsepower, is this reasonable?

 

Have you posted in the FE engine section? That's where you should ask.
I'm no expert but I think you are being unrealistic in your goal.

 

Please excuse the short reply. I hate this on the phone. Anyway you will not see 800 horses out of any na fe motor. The sohc 427 was only in the 500s maybe 600s iirc. See the fe forum and look for "survival motor sports 390" on Google. 400 to 500 with some reliability is possible with a 445 version.

 

No, not really feasible

 

An 800hp shop truck!!
Our 500ci mud race engine with 15-1 pistons, solid roller cam and 1300 cfm Holley only made 750hp on iron cj heads.
4-500hp is easily gotten from 390 but it wouldn't be a good engine for a shop truck, maybe something in the 350-400 range.

 

350-400? If I wanted that I would build a smallblock Chevrolet for half the price, but I want big power, and a Damn 4-Speed! 800 HP is really nothing I've rode in street trucks close to 900 RWHP.

 

Is that 900hp dyno proven or just all the advertised numbers added up.
You said shop truck so is it a street truck your building in your shop or a SHOP TRUCK for running after parts and hauling tools and equipment?
The super charger on the wife's truck is set for max turbine speed at 5500 engine rpm and with the other add-on's it was advertised to make an additional 3-400hp over stock. After all the tuning was done on a chassis dyno it made 361 rwhp and performance is pretty impressive for a street truck that I can tow with.

As for the original question, I've seen a full race 390 make around 650hp without power adders like super chargers or nitros

 

I have seen it on a a Dyno, it was an 93' s10 with a 400 SBC.