Lou,
You have the correct length stock. If you are going forward with a build; I'd put that one on and put a standard one on your Golani.Everyone above aready gave you an idea on the hard to get parts. The rear handguard holder would be easy.
Ugh, already told me about the guy in Canada; and Tenngalil and I bought the remaining 18 he had (he wanted to get rid of them and I worked out a price).
Personally, I would get a blank sided .223 receiver from CNC Warrior and have Jeff do a double lightning cut. I got him a good cutter last year in making this easier. I know the early R5 had an Izzy receiver; but I seen more R4's with them and I think it looks totally cool with the cuts.
I assume your going to have him do a build? He can make you a gastube that looks very real. The bolt and top cover; do have some differences (I have them on my builds), but that would be the least of my concern in getting a build going.
You also mentioned you might be able to get a gasblock w/ bayo lug; again; that is the wrong one. Barrel; I assume you are going to SBR? I think you mentioned the Replibic of Iowa doesn't allow them. Just have to get creative on your extended FH in blending it in for the R5 look.
Remember; this will be a small investment for the project; but it is very worth it in making it the best you can! So; when are you going to get started?
Ruski, Ugh is right about the thinner post being from SA.
Ady
aboard and look very forward to your input from SA; just like Ruski who has already been a big help.