Like I said I run n/a engines so spring pressures etc aren't what you guys need, but, I run titanium valves, locks and retainers. I've used 5/16 pushrods with no problem but have run the 3/8 also. Actually I prefer the 5/16 as you have more room in the head and they are a bit lighter. I use Isky lifters because they are tall and I can get away with around a 8 inch pushrod although I've seen several engines with short lifters. I just don't like the 9 inch pushrod. As far as the cam nose, I just make sure the nose of the cam is a few thousands shorter than the stack. Then when you put the washer on you make sure you get a good crush. Put a drop of Loctite on the bolt, torque it to about 45 - 50 lbs and go racing. Dont try to save a few bucks on pushrods. Buy the best you can get. For my application the key word is light, light, light. Hope that helps.