How much gear behind a v8

[zukijames]

I'm new to this v8 stuff right now I have a Lexus 1uz-fe mated to 5 speed r150f
And dual cases with 4.7s in the rear case. 4.10:1 in axle and 40 inch goodyears

If I ditch the duals It would help my rear driveline.. With the offset axle I'm worried about binding so 8 inches longer would be great.. And I wouldn't have to run a two piece front drive line.
Would ditch a little weight
And get a few $ to spend in other areas

If I keep it I will have alot of options and will have alot of middle gears that could be nice on from the 0-40 mph stuff


Motor weighs 450 lbs I guess.. (was hoping it was less than that)
290 hp
300 ft lbs of torque


Tranny ratios:

First Gear: 3.830:1
Second Gear: 2.062:1
Third Gear: 1.436:1
Fourth Gear: 1.00:1
Fifth Gear: 0.838:1


Running Fj 80 axles but adding quite a bit of weight in mounts and truss

Rig should be fairly light

Also my gfs land rover is going to be a heavy pig on tons and 40 inch tires
She's got an auto and her crawl ratio is 56.54

Is that low enough? Will it overwork the tranny?
Thanks for looking an I will remember these are just opinions and not get all butt Hurt like I did last time

Thank you all and rme for all your help

 

[zukijames]

My 1st gear options:

Low low. 168.27:1
Low 73.8:1
Higher low 35:1
High 15.7:1


Not sure if thats right I'm on my iPod and everything is a pain in the butt on this

 

[skippy]

Is this gonna be a racer or a crawler primarily? ??

 

[zukijames]

It depends how my first race goes.. That's why I like the duals.. Can keep 4.10 axle gears so I can still do 100?? Or so in high but put it in low low and crawl through boulder canyon..

I should just run an aw4 auto with a 3 speed atlas but I'm poor

I think I'll try duals and if I bind u joints then I'll sell my doubler

 

[Chevycrew]

Single case with 4.7s may be the route to go. Have you done the math to see top speed with 4.10 gears, 2.28 low with 40s in overdrive at redline? I doubt you will ever need low-low with 4.7s.

 

[zukijames]

The low low I think I'd use second gear alot I have not done the math yet i plan to tonight

 

[Karnage Fab]

witn 4.10's in th axles, id be getting an output shaft from longfield for the rear t-case. thats first on the list to break.