im looking at a 88 jeep wrangler with 140k and rebuilt i6. i was just wondering if it would be a pratical and reliable daily driver(new to jeeps). also im planning in the future to put 35s under it just wondering if its easy like leaf springs or something. also will the axles be strong enough for 35s.  

I would not go over 33's with stock axles and even with 33's if you do not regear axles it is going to be a slug at times because that year is geared pretty tall to begin with and big tires makes it worse.  If it has a lift on it now, chances are that front end is pretty worn out with that mileage.  

it only has a 4" lift with 31s nothing major.  

Lemonhead:
it only has a 4" lift with 31s nothing major.

Well with 140K miles 31's, 4 inch lift and a rebuilt motor, it has had a hard life. With proper care engine can go 200K plus. Not trying to be a downer here but if you want it, get it cheap so you can put some coin into front end or tranny if need be. (usually tranny goes before engine)