For an idea of what it would be like, pull a plug wire and take your truck for a spin. The performance should be about the same, given that 35's are 25% bigger than 28's and have a lot more rolling resistance.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed