For me....I wouldn't bother. RS option isn't a deal breaker for me and it's going to cost you a bit to get it done. As far as loosing money....unless it's an all numbers matching and I mean everything from rearend to drivetrain to interior etc then it's not really going to matter. People that usually want #'s matching want everything #'s matching.
We had a '67 RS/SS 396 that was a clone and it didn't bring any more or less than it would have otherwise. At least we felt it wouldn't have. You never really know but no one seem to have made it an issue when looking at the car.
Bumper guards.....man I love them. I wouldn't take those off at all....but that's my opinion.
If you plan on keeping it, make the car your own. Put the things you like on it. Just realize that you may not get your money out of things like that RS conversion.
Your car looks good but if it were me I wouldn't spend the money on the RS. I would spend it on some Wilwood 4 wheel discs, lower the rear with Hotckis rear springs, and bring the front down with some tubular A-arms and QA1 coilovers. I'm putting on tubular arms and QA1 on my car right now. Hope to have it finished up this weekend.
2SS | M6 | VR w/White Stripes | 1 3/4" KOOKS - 3" Magnaflow | LPE 3.91 gears | ADM tuned | Halltech w/ADM Scoop | Spohn/BMR Trailing Arm/Toe Rod | BC Coilovers| Pedders FE4 ZL1 swaybars | Cradle/Diff/Radius Rod bushings | VMax TB | Morimoto Projectors | MGW shifter | Red Calipers