I have a 1986 Chevy K30 Dually and I am wanting to run bigger tires on it and I'm running into problems witht he rear wheels.  Would it be easier to just convert to a SRW than to keep the dually and what would be required to do this conversion?  Any info or insight on this would be a great help.  

How about your front axle is it set up for srw, or drw? My guess would be drw which means you would have to change your front hub flanges, wheel studs, and maybe rotors. Now if it is set up for srw. Meaning your wheel is not off set. Then I would just swap rear axle for an srw one.  

It rear, you only need to find the right hub assembly to change on spindle. No need to swap whole axle. You should have a D70 in rear with dually that year.  

how big are you looking to go?
I run 38.5's on one of my toys (the rear has spacers in the rear) and also have a 86 chevy drw I run 34x9.50-16.5's with 34x12.50-16.5's up front.

another route I've been is 255x85-16's in the rear and 315x70-16's up front.
285's can be used on all 6 if you aren't hauling a bunch of wieght, the rear will rub without spacers, I've yet to have problems with tires blowing.