Hello I will help you with your question,
Here are the specs for the engine
The exhaust is
Let me know if you have further questions about this
Thank you
I am of the school that the parts were included in the kit because you need them otherwise they would leave them out and pocket the savings. There will be some seals and parts that are extra as they fit other applications but if I run across a seal or part and have a replacement I install it. You are correct that building an engine is meticulous work and it is very easy to overlook steps that will affect the longevity of the job.
You can chalk this off to a learning experience and plan on redoing the job correctly the next time, experience is the best teacher and sometimes we have to learn the hard way.
The intake specs are
Refit
Good luck with your brother
ASE Master Technician
ASE Master Tech 10+ yrs, AAS Automotive Technology, Factory trained Asian specialist