I ordered a 44mag BH in 5.5".  I really wanted a bisley grip, but could not find one anywhere.  I have a bisley single six at home.  I am not a ruger guy so I do not know all the intricacies of the frame differences.

Am I correct that I should be able to swap the frames?  I realize some fitting may be required.  If there's too much fitting, I'll just buy another frame.

I'm pretty sure the frames are interchangeable and there should be very little fitting, if any, needed.  IIRC, you will have to also swap out the trigger and hammer as those are unique to the Bisley.  Definitely post a pic of the completed project if you go that route.  It's a gun I'm lusting over.

You've actually given me an idea to ponder.  Like you, I've been looking for a .44 magnum Super Blackhawk Bisley (in my case, a stainless 4.62" or maybe even a 5.5").  Ruger has stubbornly refused to offer one that isn't a "Hunter" model with that giant top strap for mounting a scope.   I have a New Vaquero Bisley .45 Colt so maybe.......  Unfortunately, I love my Bisley New Vaquero so I don't think I can do it.

I could buy a Bisley frame, trigger & hammer from Brownells and swap out a plow handle .44 mag SBH but I hate the idea of having a frame sitting in a box.  I can't afford to buy two guns and do a swap.  Oh yeah, that's why I gave up on this a dozen times before.  I'm a poor lol.

This is my .45 Colt Blackhawk Bisley convertible.  I want this in .44 mag but with the 4.62" barrel.

Good point on the hammer and trigger.  I know colt saa's inside and out, but not rugers.

Edit - if I'm picturing this correctly, I think a standard hammer would go in a bisley frame, not visa versa

I'm no expert but I think you will have to use the Bisley hammer and trigger with the Bisley frame.  You can use a Bisley hammer in a plow handle frame but the hammer would have to be modified to the point it wouldn't work in a Bisley anymore.  I don't think you can make a standard hammer work in a Bisley.  

My original point being that you should be able to swap the frame out of your Single Six Bisley with your new plow handle Super Blackhawk but you will have to swap the hammer and trigger as well.  Swapping just the frame without the hammer and trigger won't work.  If that makes sense.  

Honestly, I'm no expert on the subject.  It's just something I did some research on awhile back.  I would highly recommend going to the Ruger forum and asking those guys.  There's a guy on there named "Iowegan" (I think that's how it's spelled) that's a retired gunsmith and as close to a Ruger repair god as I've ever come across.  He, or others, could definitely give you the for sure facts.

https://www.midwayusa.com/s?userSearchQuery=ruger+grip+frame&userItemsPerPage=48

You'll need to swap to the Bisley trigger and hammer as well and do a little fitting.  Power Custom sells the conversion parts but they're not cheap (if you go to their website it's a horrible throwback to the early days of internet retail).  There are multiple articles on-line detailing how to do the conversion; rugerforum.net has several threads on doing it.