I've read the last few posts here and forgive me for being repetitive if I am, but I thought I'd offer my input. I do a lot of hyd roller stuff but hydraulic is hydraulic when it comes to preload.
First, the lifters will all be at their "full" position, where the plunger is at the top of it's travel, whether the lifter has oil in it or not. Some may be filled with oil, some may have had the valve in the open position while sitting and "bled down" like Jay eluded to earlier. All hyd. lifters have a "bleed rate". Some will bleed down rapidly and some will take a while, all depending on internal clearances. Morels are known for very tight tolerances inside and very low bleed rates. Cold oil adds to this condition.
As far as setting preload; I've heard just about every method in the book, but the one I use is, first, make sure the lifter is on the base circle. Doesn't matter how you do it. TDC, EOIC, or what have you. Next, don't use the "spin" method because you can still spin a pushrod that's compressing an empty lifter and that will get you in trouble. It's very hard to determine when there is zero lash using the spin method. Start by backing off any adjustment till there is obvious lash clearance. Now, with a very light touch, grab the valve end of the rocker with two fingers and gently start rocking the rocker up and down and slowly start adjusting the adjuster till there is no lash. As you keep rocking the rocker, you will feel the lash start to decrease. Don't push on the pushrod! Just let the pushrodd sit in the lifter with it's own weight. It doesn't matter if there's no oil in the lifter or not. There is a small spring in the plunger that will keep it at it's top position. If you're not careful, it's easy to compress the lifter if it's not full of oil, so be gentle. Wiggle, tighten, wiggle, tighten...you can feel where the last few thousandths of lash goes away. This should be the same on every lifter whether its full of oil or not. Once you have zero lash, give it however much preload you're using. Ideally, you want the plunger of the lifter in the middle of it's travel so I'd say 1 full turn is minimum with 3/8" adjusters. Do this with each valve, one at a time, and you shouldn't have any trouble, at least with lifter preload. If you feel like you;re trying to compress a lifter when you stat doing the preload, give it a quarter turn, wait a minute...another quarter, wait...the lifter will eventually bleed down. You can also look at the adjusters and they should give you a pretty good idea whether everything is right or not. They should all be very close to the same number of turns, or be at the same level in the rockers. If you have some that are obviously different, you might want to re-try them. Of course if your valve stem heights are all over the map this won't be the case but then you have bigger fish to fry.
As far as push rods rubbing, I do a lot of pushrod clearancing for over sized pushrods on engines I build. My "gauge" is a piece of paper wrapped around the pushrod. If I can slide the piece of paper all the way through the pushrod hole, it has enough clearance. The pushrod will flex! Even 3/8 pushrods in an FE will flex, and flex a lot. It was mentioned and I agree...we can actually use the head (or intake in this instance) to help limit the flexing by only giving the pushrod enough static clearance so the pushrod isn't in any sort of bind throughout it's movement. If it has clearance throughout it's movement, but you're still seeing rub marks, so be it. It's fine. In fact, at that point the more clearance you give it, the more it will flex and we don't want pushrods flexing. Just picture a pole vault. We don't want the pushrod becoming a secondary spring in the valve train.
