Need "pro" opinions on my planned setup!

[tx72k15]

I'm no 4x4 guru but I know there's plenty of them around here so I wanna throw out the gear I intend to run and see what some wisdom and experience may have to say about it.

My truck is a 72 K15 custom body lifted on an 83 Suburban frame with a mostly stock suburban drivetrain. I know it's stock axles and gears but it has a "K" series 700R4. Most of the work done to the truck so far has been rust removal and other body and interior work. I also added a 4" rough country suspension lift which totals up to 10" of lift with the custom body lift. It also has an early vortec 350 with not much more than a high rise intake, edelbrock carb, hooker headers, and flowmasters.

It has 35" tires on it now and I would like to change the gears to 4.56 and upgrade to some 37" tires. JEGS has some 4.56 gears for it for $159.99 a set. Are JEGS gears worth a damn? How well will the stock suburban axles and 700R4 hold up to the bigger tires with the new gears?

The truck is never gonna be a truly hardcore rig. Atleast not any time soon. For now it is going to be something for me to be proud of and enjoy and will probably spend at least half of its time on pavement and dirt roads. I'm not gonna be scared of playing in it but its probably not ever gonna be the truck on youtube with water rolling over the hood as it crosses a small river or slamming through ruts with the gas on the floor in 4low.

Also, how do I go about allowing for the bigger tires and lower gears with the speedo? Is there an adapter you buy for the cable?

Anyone know how to use the OD on the 700R4 without the electronics? Right now it might as well be a TH350 cause only 3 gears work.

Thanks in advance for all the help,

Doyle