My Stretched Revo 5T conversion, advice pls

[Overdriven]

I've been wanting to do something like this for awhile, after seeing Lincpimp mention his savage I realized it wasn't that crazy after all. The chassis started as a 2.5, cut in half at tranny and extended 9.75in. E-revo tranny, and one looonnnggg rear driveshaft I pulled my MMM 2200 and 5s 6000 polyquest from my buggy for testing, geared 18/68 it runs 140's @ 80 ambient, with plenty of juice to end up its roof. Funny site seeing this stretch limo riding the wing down the block.

My problem is the handling. The turning radius is pretty good, and in the dirt it'll slide pretty good. On the street, lifting the inside rear tire and eventually traction rolling is a problem. I'd like the rear to slide more, like my old 3.3 revo used to. Current setup is P1 rockers, springs are white front, green rear, inner hole on A-arms f+r, sway bars stiff front, soft rear. As far as I can tell the f-r weight distribution is about the same as an e-revo. I am going to change to stiffer springs f+r, and larger diameter tires, but am looking for suggestions on spring rates, tires, other settings. Getting it to handle is a must before buying a body.

And the pics




and a little size compatison with my slash bodied buggy