How do I run 35s reliably
 

Your C8.25 will handle 35s just fine. Is your D30 a high pinion? Most people suggest 4.88 gears with 35s.

The 8.25 will be just fine. For the D30, if its not a HP, find any 97+ non ABS D30. 4.88's are about the ideal gear for 35's. Make sure you have good brakes, new hub bearings, and new rear axle bearings. You can spend money on Chrome moly axle shafts, but i dont think they are needed. Truss each axle if you like. Im currently running a set of 97 XJ axles. DPd30 and 29 spline 8.25. 35x12.5x15's. 4.88 gears, Spartan locker in the back, detroit tru-trac in the front. Daily driven 30 miles a day plus weekend 4wheeling and no issues. Be smart with the skinny pedal and you will be jsut fine. FWIW i went from 20mpg on 31's, 13mpg on 33's down to 11.3 mpg on 35's. All daily driven miles, roughly about 20k miles with the current setup.

I am building mine to run 35s and I was going to get 4.88 gears, until I saw how small the 4.88 pinion was on the Dana 30 so I went with 4.56 instead. I will be using stock Dana 30 shafts with Spicer 760 u-joints and full circle clips. Stock rear 8.25 shafts also. I do have a spare rear, and 2 front shafts that I will carry with me incase I break one.

How are the 4.56 gears doing? I bough them for mine but havent install them yet.

LOL same here, still have them sitting on the table with the rest of my suspension parts. I currently have the interior stripped and I am building some rock rails, patching some holes in the floor, and fixing some rust spots before I go over it all with bed liner. I hope to have it all up and running in the next couple of months.

I've been running 35's for over 6 years of some hard wheeling with no issues. Keep front wheel spin/speed to a minimum with a locker to save parts. I also have not gone to Alloy shafts for one reason.shafts are easier to change on the trail than a diff. I would much rather swap one out trail side with my 4.88s than grenade the whole diff. I think of my axle shafts as a woodruff key..they break before anything else expensive.

I run a HP 30 front with sleeves, c gussets, and 4.56 gears. Stock shafts and I break one every few rides. High pinion dana 30s are stronger than their low pinion counter part. I went with 4.56 since they're stronger than 4.88s. I have probably 10 spare shafts for the front, but none for the 8.25. As long as it's 29 spline it'll be hard to break with 35s. I wheel decently hard with lockers front and rear.

How is 4.56 stronger than 4.88s, I thought 4.88 would improve offroading and towing, at least that's what I read.
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4.88s have a smaller pinion that makes less contact with the gear, the teeth are smaller as well. 4.88s give you more torque but they are physically weaker than 4.56s.

Physically stronger not mechanical advantage stronger. The pinion on the 4.88 gears is tiny to get that deep of a ratio, but the 4.56 pinion is larger.