New Street Truck Build

Bout 7 years ago a "friend" told me he had a sweet truck for sale. When I got there to look at it the hood was open the whole top end was in the front seat in pieces. Foolishly of course I Bought it.A 1979 F100 ranger 4X4 red W/ black 38X14.50 super swamper TSL radials and most of a 1969 429 big block. There were litterally pine trees growing in the cylinders. So we pulled the motor and sent it to be rebuilt.It was bored out 0.030 over stock ,high comp. pistons installed, lunati Bracket Master IICam and Lifterkit,edlebrock performer 460 intake topped W/ a Holley 750 double pumper.The tranny is a C-6 3 speed autowith a shift kit and 456:1 gears for turning 4 massive mud flingers. Recently my body started to fall apart fast so I traded it for a 1981 step side 2 wheel drive short bed I pulled my motor first as it only has about 700 or 800 miles on the rebuild. I want to put my big block in the hole where the straight 6 sits now and turn it into a street / STRIP truck . Any advice is appreciated and what I really need is recommendations for new gearsto get me close to 11.5 to 12.5 seconds in a 1/4 mile. Thanks in advance.

How tall of a tire will you be running?...Any idea of how much the truck wieghs and how much power the motor makes and at what rpm??

I want to put M/T 10.5 drag radials probably 26 or 28 inches tall. the truck weighs abuut 3200 lbs W/ straight six in it havent swapped motors yet . Id like to fix everything up before install.No clue on HP wrote a post about tha the other day got no response.Im a first timer at the so tech questions are beyond me.

Well I did some basic math..I figure your truck will probably be around 3800lbs with the big block and you in it..
12.5 @ 109mph requires 385 hp
12.0 @ 114mph requires 435 hp
11.5 @ 119mph requires 494 hp

With 28 inch tires(I think the 26s would be too small on a truck)
..............4.11 gear.............4.56 gear
109 mph- 5376 rpms............5964rpms
114 mph- 5622 rpms.............6238rpms
119 mph- 5869 rpms.............6512rpms

There are lots of formula's and calculators online to play around with..There is an RPM calculator on fordmuscle in the tech section and here is another one with lots of info to play with.. ET and Horsepower Chart

How many RPMs can my enging safley turn without catastrophic engine failure

You should be able to turn around 6000 rpms briefly without too much worry..From the looks of your combo though your engine probably won't make anymore power above 5500 rpm so I would stick with that for a redline...A performer rpm or stealth intake would allow a little more useable rpm up top...As a rough example of 1/4 mile times my old setup was a 1982 F-100 with a 1969 429 thunderjet (320hp 2V version)..It was completely stock except for a set of headers and a 750 holley and stock cast iron 4V intake..It had close to 90,000 miles on it and it had the stock C-6 trans and an open 2.75 rear end...I ran the 1/4 in the 15.4 range@ a tick over 91 mph..I later discovered I had a severe vacumm leak under the carb so I'm sure it could have ran much better..The gearing obviously didn't help either as I could only use first and second gear..This was back in 1991 and I would run almost dead even with the stock 5.0 mustangs so it wasn't too bad for what it was..

thanks for your help sounds like u know your fords