Depending on what you need to index and how often, a lot of numbers can be done easily on a rotary table (anything that's a factor of 360 is really easy), which I find convenient for things like drilling holes on a PCD so use for all sorts of jobs. It is worth looking at the gear ratios of dividing heads and of rotary tables - I didn't and have ended up with a table with an odd ratio and an odd minor increment on the vernier scale (I think it's 25s seconds so even getting whole minutes is impossible).
A lot of rotary tables can easily be converted to do dividing by modifying or replacing the handle with dividing plates and an indicator arm, so if it's something you might need occasionally and not to start with, it might be worth starting with a rotary table and converting it later as required. It is also possible to use something with the right number of holes (or indentations like a gear) on the spindle with the item to be machined and index from that by making a detent to fit the holes/teeth. For example, if one needed to make a 127 tooth gear for metric threading on a SB 9" because such a thing were not available where they live, but it was possible to get a 127 tooth gear to fit some completely different application (different DP or pressure angle, possibly a module gear rather than a DP gear) then that could be attached to the same shaft as the gear blank to be machined and used to index the blank for each cut. You don't even need the worm drive of the rotary table for that, just some thing to lock the shaft in each postion.
Some dividing heads (universal) have advanced functionality beyond indexing using plates, they can be fitted with a compound gear train to acheive numbers beyond the scope of the plates, or to connect to a feed (on a milling machine generally) which enables cutting of spirals (i.e. cams).
I am not sure if 15:1 is a useful ratio for a dividing head, it's too coarse for a rotary table at 24 degrees per rotation (72:1 is more normal, 5 deg per rotation, I think mine is 90:1) but that's not necessarily such an issue for a dividing head. I would say if you have the parts it's a nice project. 6304 bearings are not hard to find - I use them for some of my kite buggy wheels, I think they are about £6 each in stainless, fortunately I don't need those wheels for the Euros next week because all 6 bearings seem to be seized, I will need 6 off 6004's for the wheels I will be using though - none are seized but they aren't feeling very smooth, probably got some sand in!
I'm not sure if I really answered your question, for occasional use you can get away with a rotary table as a dividing device, possibly vice verse although most dividing heads are not as easy to use in both horizontal and vertical orientations as most rotary tables (exceptions on both sides!), but if you are looking for something to do with the worm drive you have I reckon it would probably suit a dividing head better. I'll try andremember to look in my dividing book later and see what ratios are commonly used - unless you can find the same info on the internet sooner
Jim