Hey Buda, just how strong is that 390? Anything like the Bullit car? ENVY and more ENVY.
Speaking of 68 Mustangs with a 390fe..............My friend had a 68 fastback, but he built a 428fe for it that made 525hp on the engine dyno. It was yellow with a back stripe and was on the cover of car craft magazine in the early 2000's for an article that was called "looks stock, hauls ***." That engine was really crammed into that car, but it really hauled butt. It did an 11 sec quarter mile on pump gas without any kind of power adders. It was a very nice car.
That car was setup for drag racing. We took it out for a spin to get lunch one day.
We entered the driveway to the restaurant pretty much at a 45 degree angle, with both DOT approved slicks burning away. A huge cloud of smoke followed us into the parking lot. The patrons of the restaurant got a front row seat through the large windows in the side of the building.
When we got inside I noticed the local cops eating their lunch

Luckily they didn't say much. There is nothing quite like going for a spin in a classic muscle car
The same friend helped me install the 406 into my pickup. We took it out the afternoon that we finished it up, to put a few miles on the engine and make sure everything was working well. He wasn't too familiar with the area I live in. Headed down a 40mph street, he decided to open it up after the stop light. A couple seconds later he is doing 65-70 mph. He said it ran great. I mentioned the sheriff station that was half a block ahead of us and the driveway which they used most of the time that was within sight of my truck racing down a residential area. Of course he was comfortable with that. He was clicking off 100-120 mph between lights, when we took his car out. They crush cars when they are caught street racing in my area, by the way. As in literally put them into a junk yard car crusher as is, as a punishment. We must have hit that street while most of the sheriffs were out on patrol. At shift change, they can be pretty thick near my house.
I have a feeling that I would get into too much trouble if I had a lighter weight car with the same engine I am running in my truck. The extra weight tames it down a bit.