First I would look into getting the stock brakes working good (test brake booster, pads, calipers, shoes, springs, etc..). I have stock brakes and it stoped fine with 33's (after all of the above was new). Now that I went to 36's it takes more pressure to stop but I can still lock them up.
My 33's rubbed at the front of the rear fender when flexed up. With a little trimming my 36's only rub at the rear of the front wheel well (which I did not trim) when flexing. The worst offender is the "fang" area in front of the front tires. It rubbed when backing into my driveway before the trimming (w/ 36's).
'71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust