Realistic gearing for not-so-factory driveline

Hello All,

I have a 1979 Hilux 4x4 LB that I've had for many years and am finally ready to start seriously working on. Back when I first got it I did the older version of the All-Pro extreme lift with the heavy duty front springs and high-steer with the expectation that I'd do a larger motor than the 20R someday.

Well that someday is now. I am beginning to build my driveline. From crankshaft to rear output flange, this is what I'm cooking with:

1. 1990 Lexus 1UZ-FE Non-VVTI - Own engine, need to purchase stand alone ECU for coil-pack conversion from Spitronics, with optional idle control and USB hookup. Also need to purchase bell-housing adapter from Akina Motorsportz, include clutch kit.
2. 2002 R150F 5-Speed - Own transmission, need to purchase URD short throw shifter.
3. Crawl Box - Do not yet own, need to purchase from NW Fabworks to match chain drive build. Have donor VF2 to use for build.
4. 1994 VF1 (Chain Drive, Passenger Side Drop) - Own transfer case, passenger side drop to work with factory front axle passenger side differential location.

Now that you know my driveline idea, here's where things get interesting. In the front axle I have a 2002 4Runner E-locker with 4.30 gears, and the rear axle is from a 2003 Tacoma with a factory locker, which has 4.10 gears. I am not driving the truck right now, obviously, so don't worry about the different ratios quite yet. One or both of them is getting re-geared.

For the tires, I'm pretty sure I want to run a 37 inch. Which one? Haven't decided yet. I think it would be a good size with the 6" lift and would give me lots of clearance without being overkill. Regarding the engine, it looks like the sweet spot for highway/freeway driving with a 1UZ-FE is 2400-2600RPM. I've split the difference here and done my calculations with 2500rpm.


With the R150F's gears, and using my front differential's 4.30 gear ratio for my calculations, it looks like I can find a sweet spot for highway/freeway at around 75mph.

And with that, we come to the point where I need help. I have read lots of posts, both here and other forums, about how much Toyota pickups struggle to run a 4.10 gear ratio with 37 inch tires. I think this is usually in regards to stock engines in the 1979-1995 pickups, which range from the 20R to the 3VZ-FE.

With this in mind, and the understanding that I have a 1UZ-FE, is it reasonable to assume that the 4.30 gear ratio will be good for my truck? I would not want to sacrifice any more speed if possible since the freeways in my state are all 80mph. This would also be nice because I would only have to re-gear the rear differential.

Are there any concerns (other than starting-from-stop low end power/torque) that I should consider when running 4.30 gears? Am I missing anything?

Let me know. Thanks