It could be possible you have the wrong throw-out bearing, (too long), and you are actually trying to depress the pressure plate fingers as you put the tranny in. I agree with others that if the tranny is in far enough that the bearing retainer is hitting the back of the bell housing, you are in the pilot bushing. Do not ask how I know about the wrong throw our bearing. To check on the throw out bearing, put it in the clutch fork and hold it against the pressure plate fingers, see how close it is to the register hole in the bell housing, or use a small tape line and stick it through the center of the clutch disc and measure to the back of the throw out bearing, then measure back along the input shaft.bearing retainer and see if there is any interference, (like maybe you're close to the "step" where the machining stops on the bearing retainer where the throw out bearing rides). One other thing to check is for a "ridge" on the end of the input shaft that might be hanging on the pilot bushing. You do not want to know how I helped a "friend" find out about that one either. If you used an old input shaft to line up the clutch disc when you bolted down the pressure plate, and having the tranny in as far as you say, I'm not sure I would try the shot of pushing in the clutch to free up the clutch disc, (only as a last resort). If you try that, be ready, sometimes the throw out bearing can bind on the retainer and you will push the tranny back out, and those 833's are heavy. Good luck.

"IF YOU'RE UNDER CONTROL, YOU AIN'T GOING FAST ENOUGH."