360 - Rebuild - Information & Opinions Needed

Internal balancing adds smoothness, lifespan, power, ability to hold more power, and economy, in addition to making it easier to find a decent balancer and convertor down the road. I find it amusing that people will spend another $3-400 to go with a hydraulic roller to avoid a cam being wiped, but won't spend another $300 to get an improvement you will feel every time the car is started. Yes - internal costs a little more. Yes - it is worth every cent. We're talking about 5% of the engine build budget (based on a mild build I might build).
30° seats are a waste IMO unless you're working on a tractor engine. The factory Mopar heads are no barnstormers as cast, but they are not so bad that the seat becomes a necessary part to mess with trying to make the port work better at low or mid lifts. Simple things like a backcut on the intake valve and much higher accuracy in regard to concentricity on the valves and seats will go a long way to adding real flow all accross the lift range without compromising anything specific. Get the guides right and use top quality equipment with a machininst that knows how to use it and you're way ahead. My shop uses Serdi equipment for the seats & guides, and valve resurfacing. They cut 5 angles. It's basically a three angle using a 46° seat angle (best compromise in his experience for a street engine) and chamber and throat cuts to help the air move accross the seat. Paying a little more for the valve job frees up power and leaves you without worrying about rocker geometry and shims. Now no flow bench can truly simulate a running engine and there's all kinds of ways to pump up flow numbers that don't make for power on a running engine. But I've watched "before (running shape OEM valve job)" and "after" testing on a my customer's 596 heads on his SF600 bench that had a average increase of 8%. That's just by replacing valves with performance stainless, correcting the cuts on those valves, and doing a modern valve job on the heads themselves.