Otto - If you already have the rear shaft assembly in place, the forward end of the shaft should only fill about 1/2 of the oil feed tube assembly. Trying to picture in my head the steps you are using to reinstall.
If I'm understanding correctly, the answer to your last question is yes. It shouldn't be that difficult to get things in right vicinity and locate the support stud bolt hole in the the head. Please note that's not how I would do it though.
IIRC, you mentioned you were leaving the rocker adjusters as they were when you removed the assemblies. That will complicate your reinstallation as the rocker assemblies aren't going to rest in the proper spots on the head with the lifters/pushrods trying to open the valves in conjunction with where the cam lobes are when disassembled. That's going to make you need to use the mounting studs to draw down the rocker assemblies to sit properly, which can also coincidentally do damage to your oiler feed tube.
The better way to reinstall the rocker assemblies is to back off the adjusters so clearance from the valves exists to let the assemblies set properly. Before you do that, in tracking your previous mention about presetting the rocker adjusters to the approximate position they were before removed, you can do a thread count of the exposed adjuster threads above the lock nut and record that. Then after you've backed everything off and set the rocker assemblies, reset them to where they were originally. That would get you "in the ballpark" perhaps, to allow for engine restart and warm up to operating temp before full valve adjustments. Again, please note I'm not recommending this process.
OR (my recommended process) - You can use this "Legacy Tech Tip" on
Valve Adjustment to get your rocker settings where needed for a restart after loosening all your rocker adjustments to re-install the rocker assemblies.
It's really easier than it seems.
