OK, sooo here goes my thoughts.... 312/ T5 5spd/ 8.8 explorer rear end

T5 = 1st 3.15, 2nd 1.99, 3rd 1.33, 4th 1.00 5th .68
rear end = 3.73
2 options for rims and tires
option 1
rims = thinking 18 X 10 in back W/ 3" wider rear fenders + maybe wheel tubs
Tires = thinkin nitto invo 295/35zr/18 11.5 wide and dia 26.02

That will give me at 2150 rpm
1st 14mph, 2nd 22mph, 3rd 33mph, 4th 44mph, 5th 65mph

option 2
rims = 18X9 same fenders and tubs if need be
tires = nitto invo 275/35zr/18 10.71 wide and dia 25.55

That gives me at 2125 rpm
1st 14mph, 2nd 22mph, 3rd 33mph, 4th 44mph, 5th 65mph

Both are pretty close, do you think that will get down the road at 65 ok at 2150 rpm or will it be too sluggish

 

Just to double check some things - that T5 gearing is pretty odd from the 2 standards I have seen, most typical are:
wide:
4.03 / 2.37 / 1.49 / 1.00 / 0.86 (r=3.76)
close:
3.76 / 2.18 / 1.42 / 1.00 / 0.72 (r=3.76)

optional gearing for 1st is 3.50, 2nd 2.14, 3rd 1.39, 5th 0.76

that either is one completely custom built T5 or some really oddball (never considered for f1 swap before) unit.

that issue asside, stock tires were 28.4 dia, are you wanting that significant of a lowering that you are going with that small a tire - I think it will look funny as a shaved ape, JMHO.

your final drive ratio is fine with both of those options, you shouldn't have any issue with tearing up the clutch.

your math is either right or pretty close (my xl sheet I made only does 250 increment rpms).

You should stil able able to go 75 on the freeway without blowing the motor up (mfg spec is max torque at 2600 rpm, and you will be right in that sweet spot). Even though redline is listed as some obscene number you don't want to go over 3000. When you hit 75 ish and the top of the torque curve two things are going to happen at the same time, wind resistance will kill your chances of seeing that next 1mph faster and torque falls off like a cliff - wherever your top end is it will feel like a brick wall at that spot.

http://www.secondchancegarage.com/public/414.cfm

 

looks like I had 1st gear wrong but aside from a 3.35 1st gear my ratios are correct for a 1992-1992 5.0 mustang according to several links i found like this one Ford Mustang: Mustang Tech: Transmission and Drivetrain: Borg Warner T5 Transmission data

I actually like the looks of this one as well. I may run the numbers with this

Motorsport 79-93 Mustang 5.0 305 2.95 1.94 1.34 1.00 0.63

As for lowering, I am planning on lowering the truck . I was playin around with tire size tryin to make the numbers work but you are correct those may be too small. If that is the case, I may need to go with a 4.11 rear end

soo if I go with a 4.11 rear end and the T5 with 3.35 1.99 1.33 1.00 0.68 and roughly a 28 " tire i get 65 MPH at 2175

and if i go with the other T5 with 2.95 1.94 1.34 1.00 0.63 and the same 28" tires and 4.11 i get 65 MPH at 2000

BTW here is the calc i am trying to use

http://www.apexgarage.com/tech/gear_ratios.shtml

 

that's the exact calculator I used until I got peeved at constantly pulling up the site to try a new combo. I put together a xl spreadhsheet with all the stock transmissions and both common T-5s that you can put tire dia into and it will spit out all the figures 0-3000 rpm in 250 rpm chunks. I owe it to the community to post, but today/tomorrow I am changing www hosting - will post soon I promise.

 

My F1 with a T5 is geared similarly to yours, around 2100 at 65, 2400 at 75. That's a workable rpm for a good sized v8. You've got enough rpm for the engine to pull at light throttle with good response when you want it. I find that 45mph secondary roads make my truck a tad doggy in 5th gear. That's ok, all the other gears work fine too.