I have a '48 with the vacuum shift removed; couldn't find a vacuum unit, so I went with what I had. I had the same problem you did, and by coincidence, I had purchased a lower shift lever bushing off ebay kinda randomly, because it was so cheap. Start with that lower bushing; you'll need a press to remove and replace it, and make a note of which end is up. (might check upper fit as well). Mine was so worn it was essentially non-existent, and replacing it made all the difference in the world. Once that is tightened up,you can work your way through the linkage, placing washers to take the slop out where needed. Once it is as 'tight' as you can get it, then follow the adjustments in the shop manual. Be sure to have someone (gently) shift it once adjusted, while you are under the car(engine off;>), to make sure your linkage doesn't rub against anything it shouldn't. I had some interference with the throwout lever and clutch linkage, and I removed and bent the arm that bolts on the transmission shifting shafts (I know there is a better name for them)to give me more clearance. Wear was my biggest problem, plus a couple of people who didn't understand the system before me.
You cannot speed shift this transmission without the vacuum assist. You will inevitably hit reverse. You have to find neutral, then ease it into 2nd. "Double Clutching" may not be necessary, but it does force you to pause in neutral before going to second. And make sure all the bolts are tight, too, or it will slowly work its way out of adjustment again-heck it will do that no matter what you do...lol. Good Luck.