A few points here from the craziest revolver modder on this forum
.
Unscrewing barrels is a "female dog". Do it wrong and you can bend very important bits. I've done it and the effort involved was...well, crazy. I did succeed.
If the gun shoots well right now AND you're not also doing a caliber swap, I'd highly recommend chopping the factory barrel. This is possible to do yourself. And there's a cheap and easy solution for the front sight, as long as you're OK with going slightly non-traditional - a "barrel band" front sight:
http://americanhandgunner.com/wordpress/wp-content/uploads/2015/08/TAFFIN-3.jpg
You'd have to run the barrel a bit longer than 4.75" because you need some contact area out in front of the ejector rod. If you have access to a lathe you could spin one up yourself...and if you went that route, you could have it cover the re-crowned barrel so you don't even have to re-blue that. You attach whatever front sight you want to the band, blue the band, stick it on.
If you don't want to do a band and you're OK with drilling and tapping two holes, something like this would allow you to use whatever 1/8th rifle dovetail front sight you want, and now chopping it to 4.75" or even shorter is plausible:
http://www.midwayusa.com/product/384942/marlin-front-sight-base-marlin-882ss-39a
You'd have to cold blue the new crown but that's no big deal. You'd gain windage adjustments.
In an early state of modification my "Maurice" had something like this, with the rear sight (on a New Vaquero) hogged out some to match a Novak front:
http://imgur.com/hEc87Wl
This level of mod means the gun was no longer SASS/CAS legal except they
might have let me run it against Blackhawks. Maybe. That's what the gun looked like as of...lemme think, maybe 2011 or so?
Of course, NOW if I tried to take it to a SASS shoot the only answer to the question of "which SASS rules does it break?" is "all of them!":
http://www.thefirearmblog.com/blog/2014/03/03/maurice-frankenruger-magazine-fed-revolver/