You're on the money by using strippers to take off paint from bike frames. If you have to use emery paper make sure you keep the sanding to a minimum once you're on the metal. If you can avoid it altogether even better. Judging from the way you worded your question, it sounds like you already know to avoid sandblasting bike frames like the plague.
OK, back to your question... there has only been one process from personal experience that takes paint off efficiently and seems to leave the metal pretty much unscathed (well, from my experience anyway). Unfortunately, they won't tell me what the process is called, so consequently I can't tell you what it is either... haha!
But not to despair, there is a way to find out. I take my bike frames to an automotive engine reconditioning shop in my city, so have a look at your yellow pages and check them all out. The one I go to has a bath where they dunk engine blocks into this bath and it comes out sparkling clean. It's not an acid bath from what I can tell, because it doesn't produce an "etched" metal surface. The parts I've seen come out of there a sparkling clean. Now, I've seen the effects of acid on steel and aluminium, but this is definitely not like that. Plus, they assure me that no harm will occur to the metal.
What confounds me is the bath doesn't seem to be metal-specific. Most japanese engines and engine parts are aluminium, but they also dunk steel camshafts, valve springs, transmission gears and grease covered axles into the same goop! Same result - sparkling clean with no visible surface damage. It seems that whatever chemical reaction is going on in there, it stops (or slows down) when metal is exposed so where thicker paint is still present they can confidently leave it in there to continue without fear that the already exposed metal would "thin out."
I don't even bother giving my frames a "head start" anymore by stripping as far as I can go before giving it to them. I just take the frame as it is, stickers an all... no need to tape up exposed areas, like the BB threads, and the headset bearing seats inside the head tube. The headset bearing fit is unchanged upon re-assembly, so I know there was no metal loss due to etching. A fully intact factory-painted frame would take an over night dunk, although on one occasion we had to put it back in and I came back for it later that afternoon. I think the "soup" was kinda weak at the time due to all the other engine blocks in the bath at the time. A nearly stripped frame like yours would take less than an hour I would say.
I have sent them steel and chromoly BMX bike frames, aluminium full suspension MTB frames and components with a lot of exposed sealed bearing bores, and never had any problems. I get charged anywhere between $40 to $80 depending on the item.
In your case it might pay to describe what I've been talking about and ask if their bath is similar, and ask to view some samples of their work. To be on the safe side, it might pay to give them a test item first, (an old disposable aluminium swingarm, fork or something) - before you commit your good frame.
Sorry I couldn't make this reply a short one...
I hope it helps, and please post back if you found an automotive outfit that can do it for you. Maybe you can ask what type of chemical bath it is, and let the rest of us know.
Cheers - Pocko