I am not a king, and not any type of expert.
The fact is that with each engine that I personally build I can handle 100% of the labor and machining and balancing that goes into it. any time that anything has to be sent out to be done, you are banking YOUR engine on THEIR work- More than likely that is an open door for an issue.
My reasoning for the post comes from being a guy that has had to learn each and every aspect of building and maching one step at a time. Just like you will during building your engine.
There are many more engines built by individuals every year than built by shops like mine. I know because I talk to alot of the guys and assist them with their combinations and do alot of their balance work for jobs.
Seeing this everyday heps to find flaws with parts, and having the needed equpment makes the product better. Things like balance impact the engine so much that many people do not understand it till they have a failure.
If you build enough engines, you will have a failure. I have atleast two a year myself, but they are normally very far from normal powerplants. Any engine builder who has not blown an engine up has not pushed his skills to the limits, and has not built enough engines!
To do the job correctly (and provide all labor yourself) and not have to look to another individual except for raw parts DOES take thousands of dollars worth of tools and equipment.
If I build it, it has all my own work into it 100%. Depending on others when you are a do it yourselfer is where many problems stem during build ups, as most local machine shops care nothing about the little guy working on the "Volkswagen motor"
I'm confident that you'll build a good engine. If you need any assistance email me, 100 people a day do and I help who I can.
As far as the engine equalling what an experienced shop that has thousands of hours in R&D can do- its not happening unless you get really lucky, atleast not on your first attempt. The first attempt you shoule be more worried about making sure you get the engine stable, and free of oil leaks. This is a very progressive thing, most guys start out with a 100% stocker and work their way up the ladder. Thats what I did.
To design one of my bus engine combos to the point it is now it took me 13 cam swaps and over 3,000.00 just in cams, lifters and pushrods to get it perfect... It can only be tested in real world environments and simulations are worthless. I'm going through the same thing now with cooling system design and have been for 4 months straight. trial and error is the only way to go! If you have the drive and patience then repsect you!