I dont have an answer for you, I am sorry. But why would you swap from power to manual? Just to free up a few ponies? If that is the reasoning, I would say do a rear gear swap (maybe to 3.42's or evemn 3.73's) or put a cam in. I had bought my first monte (85 like yours) and the guy put in manual steering. I was pissed. I put power back in and I was happier.
I bought the monte I have now (85 as well, but SS) and the SS steering box is soo much better. I LOVE it. I wish I could help you but the only thing I can offer right now is my opinion. I hope it is not too late but if thats what you truly want than I wish you well with it.
But I beg you to reconsider. As the poster just before me said, he did the swap and is GOING BACK to power. If you want, I would suggest you buying a SS steering box which is quicker ratio. You will be happy you did. As for power, people lighten their car's or rip out essentials (essentials in my eyes at least) but have a stock or close to stock motor/trans/rear. That stuff in MY opinion should be done last (gutting, removing stuff). You wont free up that much horse. And also, speed math goes in the way of : For every 100 pounds you remove from your vehicle, in theory you drop a tenth of a second in the quater mile. Now, swapping your dead gears over to 3.73's you would feel INSTANTLY. It does ADD horsepower, but it launches you off the line SOO much better. Also, if you add a drag radial to your car, you will launch much harder and you wont spin. You will just hook and drag.
Listen, I got off to a tangent. Sorry, I have a tendency for doing that. I dont even know the main reason you want to swap out. Maybe it is just something you want to do and it has nothing to do with freeing up a few horse (maybe 5? Maaaaaaaaybe 10 on a stock motor?).
Wish you well either way.
God Bless