First of all, the receiver has to be cut differently to use the correct sidefolding stock (which most of the dracos don't use),
If you are doing any build and adding the side folder you are talking about you will have to change the rear trunion and then cut the receiver. Thus, it is no more work to put it on a draco than any other AK that didn't already have it. By "add a side folder
you desired" this is what I meant, a triangle side folder, the one you said you wanted. There are, of course much better stocks if function is one's priority, and at less cost, but the triangle side folders do look cool.
and then using the normal length gas system would allow me to have a longer sight radius,
Have you actually measured that? I just walked down to my safe and took some measurements. If you go with a gas block front sight combo you describe the sight radius between it and a draco will be negligable. At best you
might get an inch more than the draco. If you are adding an ultimak I have to assume it is to put a RDS on it which further makes the sight radius issue a non issue. Its just not enough difference to matter in the real world. Having the slightly shorter gas tube and everything moved back does make for a better balanced and better handling gun.
using the normal length gas system would . . . well as solve most reliability issues that typically crop up.
No, using a normal length gas system and then chopping 5-6" off of the barrel is likely going to be the cause of reliability issues. I cannot say whether a suppressor will counter that or not. Whacking at the barrel without touching the gas system is not the typical route to reliability.
I can say that AKs aren't the best suppressor hosts in the world and subsonics tend not to cycle the action. That said I still have a suppressor for an AK SBR in the works. If you know what you can expect then it isn't disappointing.
It's a much more involved build than the typical draco conversion,
I've been into Dracos since they first hit the US. I don't know what a "typical draco conversion" is. I'm not sure what a typical Draco SBR even is. I see so much variation in them. Adding a triangle or a AK100 series folder is more involved than just drilling and tapping the back plate and adding the various stocks that can be added that way. I've seen a lot of people swap rear trunions to add the stock they want.
In sum, would taking a draco, chopping the sighthood, adding a Ultimak and then adding a triangle side folder no be easier than finding another gun, adding a triangle side folder, adding a gasblock sight combo, then cutting and re-threading the barrel? Would it not provide you with what you define as a Khyber Pass (different folks think this means different things) gun, a 7.62x39 with a triangel SU74 stock? Would a factory proven 11" barrel and gas system not be better than a chopped one and an untouched or guesstimated gas system? The look and handling would be VERY VERY close and the end result likely would be better. Now if you are going to do a very detailed Khyber pass build and start with a bare receiver and go authentic markings etc, that is a different matter. If you are that into it I'd suggest skipping the ultimak. I don't think they are a common sight on khyber pass guns.
The easiest route may be, and it might even be the cheapest, to ad would be to get something like the gun linked to below and then chop the barrel once you have a stamp. That is the linked to gun's whole raison d'etre. I tend to think of the cost of draco builds based on what they used to sale for. That said I don't think one is going to find $345 Dracos any time soon. Thus, once you add the $184 or so it seems like a triangle side folder kit commands these days you may exceed the cost of the Kvar gun. This is even more true if you are not up to installing the side folder your self.
http://www.k-var.com/shop/SLR107-64.html
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In sum, I suppose ease really depends on the base gun you are starting with and what work you can do yourself. The same is surely true of cost (as wells as what parts you have and when you bought them).