I have a 1979 F-150 Shortbox. I am currently mapping out everything that I want to do to it, but am having a hard time deciding what the best motor is to put in the truck. It currently has a 351m with a C6 tranny. Everything runs ok, but does need some work. There are just so many options so I want some opinions on what you all think. I just want to make this truck a bad *****, go anywhere truck. Thanks

 

460= more weight

 

if the 351m works good it should go great i had one and it took a crazy beating (mud burnout hooking up to chevys climbing hills) it was awesome in a 250 my bro. had a 80s f150 with the 351HO that had even more power than the 351m but if you have the m id keep it but that HO was badd,we put a holley 750 double pumper on it and headers and suprisingly it burned all the gas from the 750 to much power to pull other trucks on pavement.

 

351 Windsor

 

OK, this is coming from a guy who's built all three of your options!!!
First thing first
you've got a 351M/400 Big Block C-6
BB C-6 = 351M/400- 429-460
351W = SB tranny needed = 289, 300, 302, 351W, 351C
351W= cheaper parts, less weight, lots of HP potential
460 = @700 more for parts, more weight, awsome power, torque monster!
351M/400 good power, med weight, problems with detonation( low comp to keep under check unless you run high test)
351W is what they ran in the Lightnings!
Here's what I han on my 460
punched .30 flat top trw pistons, decked heads and block, edelbrock performer 460 intake with 750 carb, Roush Racing wires, L&L nickel plated fenderwell headers, stainless ARP bolts, Head work to use 1.73 roller rockers with 3/8 screw in studs and guide plates. see pic!

Then was my 351M/400 punches .30 to a 406, flat tops, 543 cam, edelbrock intake, edelbrock 650 cfm carb, headers, accel super coil, had spark knock issues while towing unless I used mid grade or better.

351W punches out to 358 dubble roller chain, E303 camshaft, headers, vic senior heads and intake, ran 9.90 with 75 shot in a 83 mustang convertable with 8.8 3:73's and 28" slicks, c4 with manual valvebody.

I love the 460.... but if you went with a built 351W... besides having to get a different tranny you'd be better off...... I also have a set up to put dual electric fans on a 79 for under 50.00 with thermastat contolled on and off switch.

 

My friend has a 250 with 6inch lift and 38s with a 351W in it with mad power, he has no problem roasting the tires, he rebuilt it for quite a cheap price. But ive also seen some bad *** mudders with 4.6L and 5.4L with mad power and taking a beating.

 

If you have more money than you know what to do with, build up a 460 and watch the other kids in the sandbox drool.

If you want the best practical smallblock, build up a 351 windsor.

If you have a more reasonable budget in mind, freshen up the existing engine and put that cash into making the rest of the drivetrain bulletproof.