[83GMCK2500]

Truck currently: 1983 GMC K2500 400sbc/sm465/4.10 gears/33” tires.
Truck goals: ORD 2-3” lift, 6.0/NV4500/?.?? Gears/33” tires (likely 255/85R16, or 255/80R17)

For those that haven’t read my intro or did and have forgotten since I mostly lurk in the square and gmt400 sections these days: this is a forever truck, my dad is the original owner and it stays in the family. Is it possible to set this brick up (I know, aerodynamics are against me, particularly with the small lift and 33s.) to get anywhere near 20 mpg on the highway? Using an RPM calculator, in OD at 70 with those tires and 3.54 gears the RPM is ~1,819, with 3.73s RPM is ~1,917. 3.54:1 is the highest gear I can get for a Dana 60 front, so there is another limitation. I don’t want a race engine, just a bullet proof high torque truck engine, preferably on a budget. Within reason at least, I can’t just throw gobs of money at the engine. Say $4-5k tops? Is that reasonable?

I have gathered that generally speaking the cathedral port heads are best for low-end torque, but rectangular when paired with the right cam can also produce good low end torque. Either way, what is the right cam, something from TSP or a BTR Truck Cam? I see that BTR has like 5 different truck cams, 4 stage + Truck Norris…why?

For intake, I am thinking Holley dual plane ls1/2/6 intake (if cathedral port), one of their 4150 style EFI units (I do not want a front draft intake. I want the intake to look classic with original tall filter air cleaner.), electric fans, etc. Is a stroker the way to go or stay with stock bore/stroke? I assume the more cubes I add the more fuel I add, the less economy I get? Do I need to consider a range box to get a double-OD? Should I be aiming for 1,500-1,600 rpm on the highway?

If there is another thread with a similar build in mind I was unable to find it, I am open to reading through some if anyone can point a few out. I have sifted through this section, ls1tech, performancetruck, etc. As the Title says, more research = more questions.