Re: Is this a good roll cast distance?
What are you fishing for?
Since you say that you have to roll cast most of the time, and you are using a rather short rod, I assume you are stream fishing.
The necessary distance of your cast should be dictated by your situation. If 35' gets you to the spot where the fish are, then you are good! I mean, clearly you are not salmon or steelhead fishing with a 7'9" 5wt. So, assumption #2 is that you are trout fishing in tight quarters, then 35' should be plenty of distance.
Stalking your quarry is maybe more important than trying to throw a roll cast further than you can make a presentation to a trout; work on stalking the fish to within maybe 25' and then making a better cast.
My point is to not get caught up in the distance - number of feet - that your cast is. What matters is getting the fly to the fish you are pursuing.