Persia has 6 IC. Iraq has 6 IC (in its capital, the rest of the country apparantly has no industry). Saudi Arabia has 6 IC (in Riyadh, again, the rest of the country has no industry). Oman has 6 IC. Afghanistan has, IIRC, 6 IC, again, in its capital. Ethiopia has 6 IC (at least this is a little bit spread out). I almost think I see a pattern here. Yemen has 5 IC (oops). Lebanon and Syria, which do not begin the 36 scenario as independents, have 1 and 0 IC.
I wouldn't worry that you're breaking any kind of realism by changing these numbers. Paradox has created an incredibly detailed game, and it's fair enough that they focused their attention on other aspects than the size of the economies of nations that are almost certain to remain neutral.
Just for context, Montreal, which was at the time Canada's largest city, has 0 IC, while a whole bunch of much smaller Canadian cities and rural areas have lots of industry.