Doable and practical.  Not sure on the specifics of the 1867 swede, but in general the rolling block works excellent with .22 LR.   I have an original #1 .22 RF sporter, and converted another over to .45-90, but kept the original block and extractor to use it with .22.  

One thing with the small cartridge:  Use a flat extractor.  An adaptation for a ballard type extractor would be even better; I think Marlinguy has one or a picture of one that uses a T shaped slot instead of a round one for that type.  

The problem with a rotary extractor is that the cartridge can easily get in front of the extractor.  Then you have to pry it out of the chamber, and get it back behind the extractor.  

My primary .45-90 is a swedish shotgun rebarreled to .45-90.  I have a liner I made for .22 in it; and I just pry the spent cases out with a small screwdriver.  it's fired thousands of .22's.

Vall, could you post a picture of the extractor setup?  I think that would be great to be able to see how it works.  Thanks!

Thought I had more pictures, but this is the only one I had stored. I can break it down and post more if needed?

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Thanks, Vall,

That is a great photo to illustrate how it works.  I suppose the T slot was cut with a woodruff cutter.  Less possibility of putting a case ahead of the extractor with that design, and pushes the case into the chamber very well aligned.

I ended up with a #5 that someone butchered and a very heavy octagon 22 shot barrel. I have been working on as time permit. Hard to imagine a ten pound gun in 22 short. The barrel is very nice but with a 1 in 20" twist it isn't suited for much ells.
When installing a 22 rf barrel on centerfire rifles I sometimes set the chamber off center at 6 or 12 o'clock so the firing pin does not need to be moved, works good for #1 Rugers.

Bob, your #7 pretty much copies the original Remington #1 extractor for .22.  

Here's my extractor system for my Swedish shotgun RB, converted to .45-9 with a .22 liner.  Just a tiny groove in the top of the liner face to allow the screwdriver to pry the shell out.  Works excellent, has shot thousands of rounds.

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Here's an original #1 rolling block.  

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And, the breech block and extractor for another #1 RB, that was originally .22 rf, I rebarreled it to .45-90, but kept the original block and extractor to use with .22.  I haven't made a liner for it that will take the extractor, have just used the liner shown for the other rifle instead.  I should make a liner up someday, just for completeness sake.  Only take a couple of hours tops to do.

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I'd love to have a full size dedicated #1 .22 RB.  I hate having nice enough originals that I don't want to alter them.  The one I showed above is too good to put a liner in and use, but useless in it's rebored .25-10 rf configuration now.  A liner would take it back to original .22, but ruin it's history of being sent out as a .22, and later rebored and remarked to .25-10.  

I also have a small bore rolling block shotgun sporter original that I'd love to convert to a .22.  But as essentially the only original #1 sporter shotgun example I've ever seen, I can't make myself part it out.  

I parted out and rebuilt two rf rolling blocks that weren't in as nice a condition years go; I would like to have one now to rebuild as a nice .22.  One is my backup .45-90, that I showed the block above.  The other I traded to Whitey Hanson, and I believe it ended up with Vall as his .40-70.

I have plenty of actions, I think I'll make one up someday into a .22.  I could utilize the original .22 RF block I showed above.  I have a few original sporter actions, could utilize one of them.